So the sum of the two equations will equal 90. This is because they are two sections of a 90 degree angle. So you add the two equations together and set them equal to 0. So, 3x + 10 + 2x - 5 = 90. Then you add like terms, 5x + 5 =90. Then subtract the 5 from both sides, 5x = 85. Then divide both sides by 5 to get the x by itself and get the answer, x = 17
