UKMT Grey Kangaroo, 2020

Algebra Difficulty 2.0 Junior Find the answer United Kingdom

Every pupil in a class either swims or dances. Three fifths of the class swim and three fifths dance. Five pupils both swim and dance. How many pupils are in the class?

(A) $15$ (B) $20$ (C) $25$ (D) $30$ (E) $35$

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