Answer:
Or 
Step-by-step explanation:
So since we know that <u><em>all the angles in a octagon add up to 1080 </em></u>we can make a equation for this question which is down below.

So adding all that up we get this down below.

To find x we subtract 815 from 1080 and we get this.

And finally we divide 265 and 3.

So x is 88 and one-third nit it can be in decimal form like this below.
This is rounded to the nearest hundredth