MHB Number of students in a class at first

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The discussion revolves around determining the number of pupils in a class initially, given that four more joined after a week. The correct expression for the total number of pupils after a week is m + 4. When provided with the total of 40 pupils after a week, the equation m + 4 = 40 can be solved to find that there were 36 pupils initially. The answers from a book suggesting m - 20 and 30 are deemed incorrect by participants in the discussion. The consensus is that the initial number of pupils should be calculated as 36.
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There were m pupils in a class at first. After a week, 4 more pupils joined the class.

a) Find the number of pupils in the class after a week in terms of m.

my answer: m + 4b) There were 40 pupils in the class after a week. How many pupils were there in the class at first?

my answer: no answer

I'm not sure about this question.
 
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Johnx said:
There were m pupils in a class at first. After a week, 4 more pupils joined the class.

a) Find the number of pupils in the class after a week in terms of m.

my answer: m + 4

Yes, that's good.

Johnx said:
b) There were 40 pupils in the class after a week. How many pupils were there in the class at first?

my answer: no answer

I'm not sure about this question.

Here, they are telling you:

$$m+4=40$$

So, you need to solve for \(m\) to determine how many pupils were there in the class at first (because this is what \(m\) represents).

What do you find?
 
Thanks for the reply

There was a different answer that didn't make any sense to me.

The answer that I was given from the book was.

a) m - 20

b) 30.Is this incorrect?
 
Yes, I don't see how the answers given by your book could possibly be correct.
 
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