Check the picture below.
you can pretty much count those lengths off the grid.
recall that A = 1/2 bh.
Answer: x = 12
Step-By-Step: 180 - 100 = 80
Step-By-Step: 80 - 12 = 68
Step-By-Step: 68 is angle ( X + 12)
68 + 12 = 80 + 100 equals 180
A, B, and D are the correct answers