I thought I was supposed to add but I can't come up with the correct equation

Question

Find the value of x in the figure given that SU = 133.

	A)	7
B)	8
C)	11
D)	9

Answer 1

The measure of segment ST plus the measure of segment TU equals the measure of segment SU (segment addition postulate). So:

(9x - 5) + (5x + 12) = 133

14x + 7 = 133

14x = 126

x = 9