Hi there!
The two trapezoids are similar, so we can determine a common scale factor:
OL/UR = NM/TS
9/3 = 6/2
3 = 3
Trapezoid ONML is 3x larger than UTSR, so:
RS = 4, LM = y
3RS = LM
3 · 4 = y = 12.
Find x using the same method:
3UT = ON
3(2x+1) = 4x + 9
6x + 3 = 4x + 9
2x = 6
x = 3.