Solution to simple math problem again . . .

1. The problem statement, all variables and given/known data
Laura has $1.50 in dimes and nickels. She has twice as many dimes as
nickels. How many dimes does she have?

3. The attempt at a solution
12 dimes and 6 nickels, duh.

The actual question is, how would I explain this to an elementary school child who has never had any experience with systems of equations? (the way I did it)
 
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Start with variables that represent the number of each type of coin.

Let d = the number of dimes
Let n = the number of dimes.

Now translate the first and second sentences into two equations, keeping in mind that the value of a dime is 10 cents and the value of a nickel is 5 cents. (It's probably easier to write the total value as 150 cents rather than 1.5 dollars.)
 
Not sure what level of elementry school you mean, but this might work.

Do it case wise...
The number of dimes dictates the number of nickels.

Start with the most simple case...

1 nickel 2 dimes = $0.25

To small, so go bigger.

100 nickels, 200 dimes = $25

Too big.

There must be something in the middle...

Then pick someting you know is close to the answer.

10 dimes, 5 nickels = $1.50

Eventually work up or down to the answer.

However, if you're doing algrbra, try doing the system of equations.
 
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flatmaster, your approach might be better than mine. I saw the part about explaining to a kid in elementary school, but it didn't really click with me.
 
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1. The problem statement, all variables and given/known data
Laura has $1.50 in dimes and nickels. She has twice as many dimes as
nickels. How many dimes does she have?

3. The attempt at a solution
12 dimes and 6 nickels, duh.

The actual question is, how would I explain this to an elementary school child who has never had any experience with systems of equations? (the way I did it)
Use model to relate to algebraic system.
It always work
 

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