If 82, 78, and 90 are 3 of the four angles of a quadrilateral, and if the question is to find the measure of the fourth angle of the quadrilateral, then do this:
The sum of the interior angles of a quadrilateral is 360.
Let x represent the fourth angle.
82 + 78 + 90 + x = 360
250 + x = 360
x = 110
The measure of the fourth angle is 110