Since A and B are the midpoints of the legs, is median of the trapezoid.

The measure of the median of a trapezoid is one-half the sum of the measures of the bases.

So,

             (Substitute )

     (Distributive property)

             (Simplify)

                       (Subtract 13 from each side)

                               (Multiply 2 to each side)

The measure of VT is 4.