Assuming the 10 represents the circumference of the circle (not really clear in the pic) then the area of the circle is found by this equation:
Area=c^2/4pi (C being circumference, the ^2 meaning squared, and pi of course being the infinite number found by Archimedes, but normally calculated as 3.14 or 3.14)
Using that equation (substitute the C for the 10) you get 7.9577
Round this off to about 7.96, or 8. Your choice. ~Hope this helps!
The answer would be 20 because if you multiply the entire equation by five you would get 5n+n=120. Then if you solve that smaller equation it gives you 20.
