Question

In a maths class the girl to boy is 7:5 If there are 20 boys how many girls are in the class
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Answer 1

5x4=20 boys
So that means
7x4=28 girls

Answer 2

Let the total no of girls be x

the number of boys=7:5

total no of students =20

now,

no of girls =7/5=x/20

or, 20*7=5x

or 140=5x

or,x=140/5=28

therefore the number of girls =28