Answer in fraction form: x = 87/2
Answer in decimal form: x = 43.5
========================================================
Work Shown:
Supplementary angles always add to 180.
angleA+angleB = 180
(3x-5)+(x+11) = 180
(3x+x) + (-5+11) = 180
4x+6 = 180
4x = 180-6
4x = 174
x = 174/4
x = 87/2
x = 43.5
----------
Extra info:
Based on that x value, we can write,
As a check, angleA+angleB = 125.5+54.5 = 180. The answer is confirmed.