dengan cara ya,semuanya

28.
3x + 2z = 150,
120 = 2z + 2y
60 = z + y
90 = 2z, z = 45, y = 15, x = 20
45 - 20 - 15 = 10
29.
Q = S
PQS = QST
118 = QSR + RST
118 = 180 - 118 + 2x + 6
118 = 62 + 2x + 6
118 = 68 + 2x
2x = 118 - 68
x = 50 ÷ 2 = 25