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Explanation:
The ratio of boys to girls is 3 to 5, which means,
b/g = 3/5
12/g = 3/5 ... plug in b = 12
12*5 = g*3 ... cross multiply
60 = 3g
3g = 60
g = 60/3 .... divide both sides by 3
g = 20 is the number of girls
b+g = 12+20 = 32 total students in the chess club.
