If the angle depicted on top is the angle for the inside angle in the triangle, we can find x easily. a line is 180 degrees so we can do 180-151 for the right inside angle. that's 29. we can do 5x+3+9x-20+29 = 180. 14x+12=180. 14x = 180-12. 14x = 168. 168/14 = 12
