Answer:
13
Explanation:
A trapezoid is a quadrilateral (has four sides and four angles) with two parallel opposite sides. These parallel sides are known as the bases.
According to the mid segment theorem of a trapezoid, The mid segment of a trapezoid is half the lengths of the two parallel sides.
Given that TW is the mid segment, UV and RS are the parallel bases, hence:
![TW=(UV+RS)/(2) \\\\-4z+55=((-z+15)+(-3z+43))/(2) \\\\-4z+55=(-4z+58)/(2) \\\\-8z+110=-4z+58\\\\-4z+8z=110-58\\\\4z=52\\\\z=13](https://img.qammunity.org/2022/formulas/mathematics/high-school/80pj4mqhu9cwnyil2p56l6hnufs7t44t0u.png)