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Problem 61

Algebra Difficulty 1.1 Multiple choice CEMC Pascal · Canada · 2023

If 3+=53 + \triangle = 5 and
+=7\triangle + \square = 7, the value
of $++++$\$\triangle + \triangle + \triangle + \square + \square\$ is

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Official solution

Since 3+=53 + \triangle = 5,
then =53=2\triangle = 5 - 3 = 2.

Since +=7\triangle + \square = 7 and
=2\triangle = 2, then =5\square = 5.

Thus, $++++\$\triangle + \triangle + \triangle + \square + \square = 3 ×\times 2 + 2 ×\times 5 = 6 + 10 = 16$.

Source: CEMC, University of Waterloo, licensed CC-BY-NC-4.0. Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.