Answer:
11.4
Explanation:
Given these quadrilaterals are similar, all we have to do is divide 21 (ST) by 5.7 (WX). That should give us 3.6842105263, which is the scale factor. To find the length of XY, we have to divide UT (the side similar to XY) by the scale factor. UT = 42, and 42/3.6842105263 = 11.4