Answer:
x = 25
Explanation:
3x + 5 + 5x - 25 = 180 (collect like terms)
8x - 20 = 180 (add 20 on both sides)
8x = 200 (divide by 8 on both sides)
x = 25
Since they are supplementary that mean together they add up to 180 so that's why I added them together.