The measure of A is 100°. Angles A and B are supplementary. What is mB? A. mB = 10° B. mB = 80° C. mB = 90° D. mB = 180°

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .