The Operations Manager of a Mail Order House Purchases Double $\le$

Multiple Choice

The operations manager of a mail order house purchases double (D) and twin (T) beds for resale. Each double bed costs $500 and requires 100 cubic feet of storage space. Each twin bed costs $300 and requires 90 cubic feet of storage space. The manager has $75,000 to invest in beds this week, and her warehouse has 18,000 cubic feet available for storage. Profit for each double bed is $300 and for each twin bed is $150.
-What is the storage space constraint?

A) 100D + 100T $\le$ 18,000.
B) 100D + 90T $\ge$ 18,000.
C) 300D + 90T $\le$ 18,000.
D) 500D + 100T $\le$ 18,000.
E) 100D + 90T $\le$ 18,000.