#### Answer

The proof is in the following form:
Column 1 of proof; Column 2 of proof.
Thus, we have:
1. The shape is a trapezoid; given
2. A line drawn through the transversal is parallel to the two sides of the trapezoid; given
3. The diagonals are divided proportionally; If three parallel lines happen to be cut by a common pair of transversals (lines that intersect them), then the transversal is proportionally divided.