SOLUTION: Hi The number of boys was 5 times the number of girls at first. When an equal number of girls and boys joined the class, there were now twice as many boys as girls in the class. H

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Question 1175774: Hi
The number of boys was 5 times the number of girls at first. When an equal number of girls and boys joined the class, there were now twice as many boys as girls in the class. How many girls joined the class if there were 12 girls in the class now.
Thanks
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Before change,
5g boys, g girls

p boys and p girls joined.
5g+p boys, g+p girls;
system%285g%2Bp=2%28g%2Bp%29%2Cg%2Bp=12%29


--

g=12-p
-
5%2812-p%29%2Bp=2g%2B2p
60-5p%2Bp=2%2812-p%29%2B2p
60-4p=24-2p%2B2p
60-4p=24
15-p=6
highlight%28p=9%29------------9 girls joined