Michellw, let's work backward.
A ratio of 3:4 means we have 7 total parts, so our total must be a multiple of 7. We went from a ratio of 3:2, meaning our total had to have been a muliple of 5. The difference between the two is 12.
7 + 12 = 19, not a multiple of 5.
14 + 12 = 26
21 + 12 = 33
28 + 12 = 40. There we go.
If we had 28 and 7 total parts, each part has 4 kids. That's 12 boys and 16 girls.
Add the 12 boys who left and we have 24 boys and 16 girls, 3:2.
Add the 5 girls and we started with 24 boys and 21 girls.
