Answer :
Let
Boys = b
Girls = g
The number of boys and girls in a class are in the ratio 7:5
b:g=7:5
b/g=7/5
b5=g7
b5/5=g7/5
b=g7/5...............(1)
the number of boys is 8 more than the number of girls
b=g+8.............(2)
Put the value of b from (1) to (2)
g7/5=g+8
5*(g7/5)=5*(g+8)
g7=5g+40
g7-g5=40
2g=40
2g/2=40/2
g=20
Put the value of g in (2)
b=20+8
b=28
Boys are 28 and Girls are 20
let boys be 7x
let girls be 5x
7x=5x+8
7x-5x=8
2x=8
x=8/2
x=4
No.of boys=7x=7*4=28
No.of girls=5x=5*4=20
Therefore, total strength=28+20=48
let girls be 5x
7x=5x+8
7x-5x=8
2x=8
x=8/2
x=4
No.of boys=7x=7*4=28
No.of girls=5x=5*4=20
Therefore, total strength=28+20=48