Answer
$120^{\circ}$
Work Step by Step
We can see that $\angle{APB}$ and $\angle{CPA}$ show supplementary angles, so their sum will be equal to $180^{\circ}$.
We need to find $\angle{CPA}$
$\widehat{CPA}+60^{\circ}=180^{\circ}$
or, $\angle{CPA}=180^{\circ}-60^{\circ}=120^{\circ}$