The number of sides in a regular polygon having measure of an exterior angle as $72°$ is .

Find the value of $x$ in the given figure (write the answer without degree symbol):

Three angles of a quadrilateral are $50°, 40°$ and $23°$. If its fourth angle is $x°$, find the value of $x$.

Each interior angle of a polygon is $108°$. Find the number of sides of the polygon.