单选题
A school supply store sells only one kind of desk and one kind of chair，at a uniform cost per desk or per that of 1 desk and 3 chairs．then the total cost Of 4 desks and 1 chair is how many times that of 1 desk and 4 chairs?
【正确答案】
E
【答案解析】Let d represent the cost of 1 desk and let c represent the cost of 1 chair. It is given that 3d + c = 2(d + 3c). It follows that d = 5c. Then 4d+ c = 21c and d+ Ac = 9c. Since 21c/9c= 7/3, the total cost of 4 desks and 1 chair is 7/3 times that of 1 desk and 4 chairs. The correct answer is E.