- #1

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## Homework Statement:

- Subtracting mixed numbers

## Relevant Equations:

- Least common multiple

I really can t find my mistake here 17/20 is the proper answer

Thanks

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- Thread starter chriscarson
- Start date

- #1

- 161

- 21

## Homework Statement:

- Subtracting mixed numbers

## Relevant Equations:

- Least common multiple

I really can t find my mistake here 17/20 is the proper answer

Thanks

Last edited by a moderator:

- #2

berkeman

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When you put the 3 fractions over the common denominator of 20, it looks like you did not convert the numerators correctly.

First step is to put the front whole number of each quantity into the numerator of each fraction without changing the denominator yet. So ##5\frac{3}{4} = \frac{?}{4}##

Then after you have converted each of the 3 quantities to pure fractions, go ahead and multiply to put them over the common denominator of 20. Does that work for you?

First step is to put the front whole number of each quantity into the numerator of each fraction without changing the denominator yet. So ##5\frac{3}{4} = \frac{?}{4}##

Then after you have converted each of the 3 quantities to pure fractions, go ahead and multiply to put them over the common denominator of 20. Does that work for you?

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- #3

DaveC426913

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[ DUPE ]

- #4

berkeman

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(Great minds think alike!)[ DUPE ]

- #5

DaveC426913

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Heh. I was commenting on what appears to be a different error: -3/20 magically becoming 17/20.

But I see what the OP is doing. He's actually doing 1 plus -3/20, which does equal 17/20.

The OP is trying to solve the problem by splitting the number into whole and fractions and dealing with them separately:

= (5 -1 -3) + (3/4 -2/5 -1/2)

= 1 + (etc.)

This actually does result in the right answer (and frankly, it's easier math).

But I see what the OP is doing. He's actually doing 1 plus -3/20, which does equal 17/20.

The OP is trying to solve the problem by splitting the number into whole and fractions and dealing with them separately:

= (5 -1 -3) + (3/4 -2/5 -1/2)

= 1 + (etc.)

This actually does result in the right answer (and frankly, it's easier math).

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- #6

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I will try to understand it like you are showing me , thanksWhen you put the 3 fractions over the common denominator of 20, it looks like you did not convert the numerators correctly.

First step is to put the front whole number of each quantity into the numerator of each fraction without changing the denominator yet. So ##5\frac{3}{4} = \frac{?}{4}##

Then after you have converted each of the 3 quantities to pure fractions, go ahead and multiply to put them over the common denominator of 20. Does that work for you?

- #7

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I think you mean I make magics lol[ DUPE ]

- #8

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First step is to put the front whole number of each quantity into the numerator of each fraction ? can you tell how please ?

First step is to put the front whole number of each quantity into the numerator of each fraction without changing the denominator yet. So ##5\frac{3}{4} = \frac{?}{4}##

Then after you have converted each of the 3 quantities to pure fractions, go ahead and multiply to put them over the common denominator of 20. Does that work for you?

- #9

DaveC426913

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Let's start simply.First step is to put the front whole number of each quantity into the numerator of each fraction ? can you tell how please ?

For the number 1 1/2, what would that be as a fraction only?

- #10

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if you can post a picture with a written work like mine should help me better thanks

- #11

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3/2 ?Let's start simply.

For the number 1 1/2, what would that be as a fraction only?How many halves are there in and and a half?

- #12

DaveC426913

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Sorry.if you can post a picture with a written work like mine should help me better thanks

- #13

DaveC426913

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OK, how did you get that from 1 1/2?3/2 ?

- #14

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2*1+1OK, how did you get that from 1 1/2?

- #15

DaveC426913

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Perfect.2*1+1

Can you do the same for 5 3/4?

- #16

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23/4Perfect.

Can you do the same for 5 3/4?

- #17

DaveC426913

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Perfect. Now the other two in your problem.

- #18

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7/5 oh so my mistake was that i was making /20 ?Perfect. Now the other two in your problem.

- #19

DaveC426913

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You're gonna do that next.7/5 oh so my mistake was that i was making /20 ?

Show all your work so far.

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- #21

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You're gonna do that next.

Show all your work so far.

- #22

berkeman

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- #23

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don t ask me why but I tried this already but somehow had different answer so I gave up

well thank you all

- #24

Ibix

Science Advisor

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It's very, very easy to make mistakes with this kind of work, no matter how experienced you are. If you think you know how to do something but get the wrong answer, turn the page and try again. There's a fair chance you just wrote a number wrong somewhere...don t ask me why but I tried this already but somehow had different answer so I gave up

well thank you all

- #25

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The thing is that here it worked out without make them as fractions

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