The angles of all triangles should always sum up to be 180, so knowing this we can solve this problem using the equation x + 3x + 5x - 54 = 180, first we want to combine all our common variables, so we add the x’s together and get 9x - 54 = 180 then we add +54 to both sides so that the x can be by itself and we have 9x = 234, we divide both sides by 9 and get our final answer of x = 26
