Answer
71
Work Step by Step
Let $\angle A$ be the angle. Write and solve an equation.
$m\angle A+(m\angle A-52)=90\longrightarrow$ definition of complement
$2m\angle A - 52=90\longrightarrow$ combine like terms
$2m\angle A=142\longrightarrow$ addition property of equality
$m\angle A=71\longrightarrow$ division property of equaliity
