If the radical, is the same in this case ✔️10, simply add or subtract the whole numbers or the coefficients of the radicals regularly, the solution would be 1✔️10 or simply ✔️10.
πr² = π.5.5 = π25 units² or 78.5 units²
hope it helps...!!!
Add and subtract as normal however just make sure you are always moving the decimal point in the right place.