An office manager has $11,000 to spend on new equipment. He planned to purchase 400 chairs for $72 each. He completed the calculations and concluded that there would be plenty of money left to buy additional equipment. Answer problems 4–6. LOADING... Click the icon to view the calculations. 4. What does the office manager do to support his thinking? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A. He does a calculation to find the cost of 400 chairs and compares the amount to $ nothing. (Type a whole number.) B. He does a calculation to find the cost of the additional equipment. C. He does a calculation to find the cost of 72 chairs. D. He does a calculation to find the difference between the cost of 400 chairs and the cost of the additional equipment and compares the amount to $ nothing. (Type a whole number.)