math
posted by t .
there were 490 altogether in 2 groups. group A consited of only boys and group b constied of only girls. ther were 2 and a half times as many girls as boys. some girls joined group b and foe every 4 boys in group a 32 more boys jioned the group. the total number og girls was then one third the total number of boys. express the number of girls who jioned group b as a fraction of boys who jioned group a

to begin, A = 5/2 B
a boys joined A
32/4 = 8, so 8A boys joined the group.so, A = 1/8 A
b girls joined B
So, now there are
B+b = 1/3(9A) = 3A
5/2 A + b = 3A
b = 1/2 A
b = 1/2 * 1/8 A = a/16
example:
A=12
B=30
A/4 = 3, so 3*32 = 96 boys joined A, making 18 boys in all
B+b = 108/3 = 36
so, 6 girls joined, or 96/16 
sorry about the mistyped capitalization. The lines in error should read
a = 1/8 A
and
b = 1/2 * 1/8 a = a/16
and there are 108 boys at the end, not 18