The surface area of a cylinder is given by

which is the surface area of cylinder A.
To compute the surface area of cylinder B, we have to map
and we have the following formula

If we manipulate the second expression, we have

Which implies

The meals for all 9 cost 9x5 = $45
225-45= $180 which represent the entrance fees for all 9.
We divide that to 9 and we get the entrance fee per student!
180/9 = $20 / fee per student!