So...I'm completely stumped. Any help on these would be GREATLY appreciated.

1. A rancher has 360 yards of fencing with which to enclose two adjacent rectangular corrals, one for sheep and one for cattle. A river forms one side of the corrals. Suppose the width of each corral is x yards.

a) express the total area of the two corrals as a function of x.

b) find the domain of the function

2. A rectangular box with volume 320 cubic feet is built with a square base & top. The cost is $1.50/square foot for the bottom, $2.50/square foot for the sides, and $1/square foot for the top. Let x=the length of the base, in feet.

a) Express the cost of the box as a function of x.

b) find the domain of the function

c) what dimensions minimize the cost of the box?