You can
put this solution on YOUR website! .
If x is the measure of the exterior angle, then the measure of the interior angle is 3x.
Then your equation is x + 3x = 180 degs, which implies x = 45 degs.
Thus the exterior angle is 45 degs.
Then the number of sides is n =
= 8.
( The sum of exterior angles of any (convex) polygon is 360 degs ).