The measure of TU is 15.
We set up a proportion to solve this. Using the similarity statement, we know that MN is proportional to ST, NO is proportional to TU, OP is proportional to UV, and PM is proportional to VS.
NO/TU = OP/UV
10/x = 4/6
Cross multiply to solve it:
10*6 = x*4
60 = 4x
Divide both sides by 4:
60/4 = 4x/4
15=x