I have 2 word problems that I am having trouble with:

The surface area of a cylindrical can of radiusrand heighthis

2pi rsquared + 2pi r h.If the can is twice as high as the diameter of its top, express its suface areqaSas a function ofr.

and:

A rectanular region of 6000 square feet is to be fenced in on three sides with fencing that costs $3.75 per foot and on the fourth side with fencing that costs $2.00 per foot.

a.Express the cost of the as a function a function of the lengthxof the fourth side.

b.Find the domain of the function.

Any help would be greatly appreciated.