Answer:
x = 4
QS = 20
Explanation:
PS is all the numbers added together.
PQ + QR + RS = PS
(PLUG IN)
8 + 3x - 1 + 9 = 28 (collect like terms)
3x + 16 = 28 (subtract 16 on both sides)
3x = 12 (divide by 3 on both sides)
x = 4
QR + RS = QS
(PLUG IN)
3(4) - 1 + 9 = QS (distribute)
12 - 1 + 9 = QS (collect like terms)
20 = QS
Hope this helps ya!!