3 inside angles need to = 180, since it is a right triangle, the bottom left angle = 80 so the other 2 angles need to equal 90 degrees
so you have:
(8x+2) + (9x+3) = 90
combine like terms to get:
17x+5 = 90
subtract 5 from both sides:
17x = 85
divide both sides by 17
x = 85/17 = 5
x = 5
