Question: total of 40 students in class, boys number is double of the girls number. How many boys & girls in the class?

Question

Working as follow:

a = boy b = girl

2a + b = 40

2a + 2a = 40

4a =40
a =10

b=2a

b = 2x 10
b = 20

So a=10, b= 20. Total only 30, not 40 . Why?

Thanks

Answer 1

So girls make up 1/3 of group, while boys make up 2/3.

1/3 *40 = 13. 3 rounded to 13

40 - 13 = 27

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