Postal requirements specify that parcels must have length plus girth of at most 84 inches. Consider the problem of finding the dimensions of the square-ended rectangular package of greatest volume that is mailable.

(a) Draw a square-ended rectangular box. Label each edge of the square end with the letter x and label the remaining dimension of the box with the letter h.

(b) Express the length plus the girth in terms of x and h.

(c) Determine the objective and constraint equations.

(d) Express the quantity to be maximized as a function of x.

(e) Find the optimal values of x and h.