In a trapezoid, the segment at the midpoint is the average of the other two bases.
In other words: YZ = (QR + TS) / 2
5x + 1 = ( (2x + 7) + 19 ) / 2
2(5x + 1) = 2x + 26
10x + 2 = 2x + 26
8x = 24
x = 3
YZ = 5x + 1
YZ = 5(3) + 1
YZ = 15 + 1
YZ = 16
Hope this helps!
