f(r)= (π*r^2)/2 + 3r
Basically, when they say find the area as a function, they want you to make an equation so the answer will stay proportional based on what the variable (in this case r) equals. So, in the equation I gave you, if you find the value of r, you have the answer. But, since we do not have the value of r, we must simply create a function based on the data we do have...I hoped this helped you:)