Solve for X if MN =81
A)9
B)10
C)11
D)12

Answer:
D
Step-by-step explanation:
You can see, MN consists of the three lines in the picture. So you just need to sum them tougher in an equation with it's original value 81.
5 + 3x - 8 + 4x = 81
7x = 81 + 3
7x = 84 / : 7
x = 12