Having a very hard time. Can someone please help. Im trying to find how many sides a polygon has if, the difference of the interior and exterior angles is 100 degrees?

Just use what yo know about the interior and exterior angles. If there are n sides, you want

180(n-2)/n = 360/n + 100
180n-360 = 360 + 100n
80n = 720
n = 9

check:
180*7/9 = 40+100