Question

In class x of a school the ratio of the number of boys to that of girl is 4:3.if there were 20 more boys and 12 less girls,then the ratio would have been 2:1.how many student were there in the class

Answer 1

let girls = x 
let boys = y 
then ,
y/x = 4/3
y+20/x-12 = 2/1

y/x = 4/3
y = (4/3)x
(4/3)x+20/x-12 = 2/1
now you can find x