There are two ways to solve this problem. First of all, this quadrilateral is a trapezoid because the top two angles are congruent and there is one pair of parallel lines. One way to solve the problem is to remember all trapezoids have a measure of 360. So, mD=360-(108+108+72); this equals 72. Additionally, in a trapezoid, the bottom two angles are always congruent; therefore, angle D must equal 72 degrees.
