A 30-in_-by-60-in. sheet of cardboard is folded in half to form a 30-in_-by-30-in. rectangle as shown in the accompanying figure. Then four congruent squares of side length x are cut from the corners of the folded rectangle. The sheet is unfolded, and the six tabs are folded up to form a box with sides and a lid. Complete parts (a) through (f) below. 7 k= . : == : 30 | | ! = x | ! x x T fe 60in >f le30in>f e 0in a. Write a formula V(x) for the volume of the box. V(x)= b. Find the domain of V for the problem situation and graph V over this domain The domain is (Use interval notation.) Choose the correct graph of V below. O A