Cabinet X costs $120, requires 18 sq ft of floor space, and holds 36 cu ft of files. Cabinet Y costs $140, requires 6 sq ft of floor space, and holds 30 cu ft. To get maximum storage, how many of each should be purchased with a budget limit of $1680 and floor space of 162 sq ft? The manager should buy of cabinet X and of cabinet Y. (If two possibilities provide maximum storage, use the option that involves buying at least one of cabinet X and at least one of cabinet Y.)