as we know there are 7:3 ratio then, we know that it is 7/3
We also know that boys are 60 more than girls, so if girls are x than boys are x+60 so 7/3 = x+60/x
7x= 3(x+60)
7x= 3x + 180
7x-3x = 180
4x= 180
x= 45 so boys are x+60= 45+60=10
Ps. See the picture if you don’t understand
Text me for any questions