I have 2 more questions on Optimization...I could not figure this one out; I found the language of the question confusing on the first problem

1) A silo (base not included) is to be constructed in the form of a cylinder surrounded by a hemisphere. The cost of construction per square unit of the surface area is twice as great for the hemisphere as it is for hte cylindrical sidewall. Determine the dimensions to be used if the volume is fixed and the cost of construction is to be kept at a minimum. Neglect the thickness of the silo and the waste of construction

2) It costs you C dollars each to manufacture and distribute backpacks. If the backpacks sell at X dollars each, the number sold is given by...

N=[A/X-C] + B(1oo-x)

A and B are positive constans. What selling price will maximize a profit?

Any help is greatly appreciated!