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UKMT Senior Mathematical Challenge, 2021

Algebra Difficulty 1.0 Junior Find the answer United Kingdom

The positive integer $k$ is a solution of the equation $(k \div 12) \div (15 \div k) = 20$ . What is the sum of the digits of $k$ ?

(A) $15$ (B) $12$ (C) $9$ (D) $6$ (E) $3$

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