An aquarium (without top) of height 1.5 feet is to have a volume of 6 ft3. Let x denote the length of the base and y the width. (1) Express y as a function of x. (2) Express the total number S of square feet of glass needed as a function of x.

Volume is expressed in cubic feet, not square feet. Square feet is area.

The volume is then (3/2)xy=6. Solve for y and it'll be in terms of x.

Picture the aquarium and use the area formulas to count up the area of each panel.

After you have that, you can sub in your y from the first question and the surface area will be in terms of x.