Lee Soon Yang's answer to Aisah's Primary 4 Maths Singapore question.
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Since there are 4 times more man than woman
Using expression n, man is equal to 4N, woman is equal to n
After 300 man left and 174 woman entered, both genders were equal. Thus,
4n-300 = n+174
3n=474
N=158
Total at the start is, 4n + n = 5n
Thus 5n= 790
Therefore there was 790 people at the start
Using expression n, man is equal to 4N, woman is equal to n
After 300 man left and 174 woman entered, both genders were equal. Thus,
4n-300 = n+174
3n=474
N=158
Total at the start is, 4n + n = 5n
Thus 5n= 790
Therefore there was 790 people at the start
Date Posted:
5 years ago
Thank you very much. May I also know why you add 300 and 174? To me 300 men have left, so I think I should minus.
So for the expression,
4n-300=n+174
The goal is to make all the n be on the left side and the numbers to be on the right side.
So to move the -300 from the right to the left, i need to add 300 on both side. So,
4n-300 + 300 = n+174 +300
4n = n+474
To move the n from the right side to the left side, i subtract n from both side. So,
4n - n = n + 474 - n
3n = 474
In math, when you write an expression with equal, it means both side are the same. To make changes to one side means you have to make changes to the other side.
Hope this answer your questions :)
4n-300=n+174
The goal is to make all the n be on the left side and the numbers to be on the right side.
So to move the -300 from the right to the left, i need to add 300 on both side. So,
4n-300 + 300 = n+174 +300
4n = n+474
To move the n from the right side to the left side, i subtract n from both side. So,
4n - n = n + 474 - n
3n = 474
In math, when you write an expression with equal, it means both side are the same. To make changes to one side means you have to make changes to the other side.
Hope this answer your questions :)
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