Jerry bought 48 firecrackers for the 4th of July. A police officer discovered and confiscated 12 of them. 1/6 of the remaining ones were defective. If Jerry set off half the good firecrackers, how many firecrackers did he set off?
Step-by-step reasoning:
15
First subtract the 12 confiscated firecrackers from the original number: 48 firecrackers - 12 firecrackers = 36 firecrackers.

Then multiply this number by 1 / 6 to find how many were defective: 36 firecrackers * 1 / 6 = 6 firecrackers.

Then subtract the defective firecrackers to find how many were good: 36 firecrackers - 6 firecrackers = 30 firecrackers.

Then divide this number in half to find how many firecrackers Jerry set off: 30 firecrackers / 2 = 15 firecrackers.

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Therefore, the answer is 15