The exterior angles of triangle UVW are X, Y, and Z, and they are adjacent to U, V, and W, respectively. If mV is 91°, and mZ is 120°, what is mU?

The measure of angle U is 29 degrees. Triangles have general properties which include, all interior angles add up to 180 degrees, all exterior angles add up to 360 degrees and adjacent interior and exterior angles add up to 180 degrees. In the given, exterior angle Z is 120, while its adjacent interior angle is unknown. To get W, subtract 120 from 180 degrees. The value of W is 60. With 2 known interior angles, subtract 60 and 91 from 180 to get the measure of angle U.