the class is 50 students 30 like chocolate, 25 like vanilla, and 18 like both, which like neither.

2 answers

If 18 like both, then (30-18) like just chocolate and (25-18) like vanilla.

50 - 18 - 12 - 7 = ?
18÷2=9
30-9=21
25-9=16
16+21=37
50-37=13