Answer for A:
x = -56/31
Step-by-step explanation:
The total angle for a pentagon is 360°
100 + 20(-56/31) + 140 + 160 - 5(-56/31) + 16(-56/31) + 16 = 360
100 + -36.1290322581 + 140 + 160 + 9.03225806452 + 28.9032258065 + 16 = 360
If you copy that into a calculator you will get
360°
Answer for B:
The angle for C, rounded to the nearest tenth, is 44.9°
