Question

In a class of 80 seniors, there are 3 boys for every 5 girls. In the junior class, there are 3 boys for every 2 girls. If the two classes combined have an equal number of boys and girls, how many students are in the junior class?

Answer 1

If there are
3x senior boys and 5x senior girls
3y junior boys and 2y junior girls

3x+3y = 5x+2y
3x+5x = 80
so, x=10
and y=20

juniors have 60 boys and 40 girls.
seniors have 30 boys and 50 girls

Answer 2

3+5=8
80/8=10
x=10 YES
b=30 YES
g=50 YES

y=10 NO
b=30 NO
g=20 NO
Because 60 doesn't = 70
y=20 YES
b=60 YES
g=40 YES
Because 90 = 90
S = 30 boys and 50 girls
J = 60 boys and 50 girls