Consider the following scenario in a geometric figure. Two lines, line $A$ and line $B$, intersect at point $P$, forming four angles. One of the angles, angle $APB$, measures $x$ degrees. The angles adjacent to angle $APB$ are angle $BPC$ and angle $APD$. If angle $BPC$ measures $50^{ ext{o}}$ and angle $APD$ measures $80^{ ext{o}}$, determine the measure of angle $APB$.
Recall that the sum of the angles around point $P$ must equal $360^{ ext{o}}$.