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UKMT Junior Kangaroo, 2019

Combinatorics Difficulty 2.0 Junior Find the answer United Kingdom

Ellis's Eel Emporium contains a large tank holding three different types of eel: electric eels, moray eels and freshwater eels. A notice on the tank reads as follows:

All the eels are electric eels except 12
All the eels are moray eels except 14
All the eels are freshwater eels except 16

How many eels are in the tank?

(A) $42$ (B) $33$ (C) $24$ (D) $21$ (E) $20$

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