Answer:
C. x=42
Step-by-step explanation:
16 + 3x + y = 180
126 + 16 + y = 180
y = 38
16 + 3x + 38 = 180
54 + 3x = 180
3x = 126
x=42
x= -3
-x+3(5)=12
-x+15=12
15-15=0 12-15=-3
-0.5
-4.7+4.2 = -0.5