algebra
Classes A and B have 35 students each. If seven girls shift from class A to class B, then the number of girls in the classes would interchange. If four girls shift from class B to class A, then the number of girls in class A would be twice the original number of girls in class B. What is the number of boys in class A and class B?
Please help. I'm not able to form a correct equation to solve.

I am assuming that the 2nd shift follows the first shift
now:
let the number of girls in A be x
let the number of girls in B be y
after 1st shift:
A has x7
B has y+7
"the number of girls in the classes would interchange"
> y+7 = x
2nd shift
A has x7 + 4 = x3
B has y+7  4 = y3
" the number of girls in class A would be twice the original number of girls in class B"
> x3 = 2y or x = 2y+3
so 2y+3 = y+7
y = 4
x = 11
so originally, there were 24 boys in A and 31 in Bposted by Reiny
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