Question

A group of 20 friends were going on a picnic 7 friends were playing basketball and 5 friends were having snacks if 2 friends were doing both how many friends were playing basketball

Answer 1

The problem statement tells you "7 friends were playing basketball".

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It appears 5 friends were only playing basketball, 2 friends were playing basketball and having snacks, and 3 friends were only having snacks. Apparently, 10 friends were doing neither of those activities.