Solve the following math problem step by step. The last line of your response should be of the form Answer: \boxed{$Answer} where $Answer is the answer to the problem.

<image>If $\overline{PQ} \cong \overline{UQ}$, $\overline{PR} \cong \overline{RT}$ and $ m ∠ PQU = 40 $, find $ m ∠R $.