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AMC / AIME · Inclusion-Exclusion · Easy

Inclusion-Exclusion: Sets math satisfy math, math, math. Find math.

Unions without double-counting.

Try the problem

Sets A,BA,B satisfy ∣A∣=20|A|=20, ∣B∣=15|B|=15, ∣A∩B∣=8|A\cap B|=8. Find ∣A∪B∣|A\cup B|.

Hint and answer

Concept to use

Two sets.

Hint

∣A∣+∣B∣−∣A∩B∣|A|+|B|-|A\cap B|.

Answer

27

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