Answer:
x = 5
Step-by-step explanation:
It can help a lot to draw a diagram, if one is not provided. There is no requirement that it be drawn to scale. It just needs to be able to show the given information.
Given angle QRS is exterior to the triangle. Its measure is the sum of the two given remote interior angles:
8x -9 = (3x -11) +(3x +12)
2x = 10 . . . . . . . add 9-6x and simplify
x = 5 . . . . . . divide by 2
