Angles of Intersecting Lines

Consider two lines, $line1$ and $line2$, that intersect at point $P$. The measure of angle $APB$ is 75 degrees, where $A$ and $B$ are points on $line1$ and $line2$, respectively. What is the measure of the angle $BPC$ where $C$ is a point on $line2$ such that lines $line1$ and $line2$ make a straight angle at point $P$?