Alex is writing statements to prove that the sum of the measures of interior angles of triangle PQR is equal to 180°. Line m is parallel to line n. Line n is parallel to line m. Triangle PQR has vertex P on line n and vertices Q and R on line m. Angle QPR is 80 degrees. Segment PQ makes 40 degrees angle with line n and segment PR makes 60 degrees angle with line n. Which is a true statement he could write? Angle PRQ measures 40°. Angle PQR measures 60°. Angle PRQ measures 80°. Angle PQR measures 40°.