Well I don't know if you are looking for the variable but here it is :)
I think it’s 25 and two half’s
Given problem;
A = 4 π R²
To solve for R, we have to make it the subject of the expression.
Since
A = 4 π R² , follow these steps to find R;
Multiply both sides by
A x
=
x 4 π R²
= R²
Then find the square root of both sides
√R² =
R = 
The solution is 
50% of 40 is 20, and 40% of 50 is 20, neither one is greater, they're equal
If your trying to figure out (x) then the answer would be 7 because 7 times 2 is 14 and then 14 minus 3 would be 11