Help?

I saw an answer on this website before but that was wrong and I still dont understand.

Let R be the circle centered at (0,0) with radius 10. The lines x = 6 and y = 5 divide R into four regions $R_1$, $R_2$, $R_3$, and $R_4$. Let $[R_i]$ denote the area of region $R_1$. 

If $[R_1] > [R_2] > [R_3] > [R_4],$

then find $[R_1] - [R_2] - [R_3] + [R_4]$. 

I found the previous answer of 105 but it was incorecct and I didnt understand how they got it. If you can give an explnation and an answer that would be great!

Thanks in advance!!!