26.
3x + (x + 15) + x = 180°
(add all the x's together)
5x + 15 = 180°
(subtract 15)
5x = 165°
(divide by 5)
x = 33°
28.
x + (x + 38) + (x + 55) = 180°
(add all the x's together) (add 38 + 55)
3x + 93 = 180°
(subtract 93)
3x = 87°
(divide by 3)
x = 29
