Answer:
C. 12.5
Step-by-step explanation:
If you round it into the nearest half, you'll get 12.5.
You add up all the sides, so for example, the first 1, 5+4+5+4=18
2(3x)=1(4x-1)
6x=4x-1
Subtract 4x from each side
2x=-1
Divide each side to get x=-1/2
Your answer would be -1/2
