prep破解DS上50题

evelyn205205

A construction company was paid a total of $500,000 for a construction project. The company's only costs for the project
were for labor and materials. Was the company's profit for the project greater than $150,000 ?
(1) The company's total cost was three times its cost for materials.
(2) The company's profit was greater than its cost for labor.

此题的答案选择的是C。
不理解这道题，不知道怎么一个思路
望各路NN的帮助
谢谢啦~

huxleyxu

个人理解是C 根据两个条件 设cost for m为a
total cost=cost for m +cost for labor
total cost=3倍的cost for M  thus   cost for labor=2* cost for m
total cost=3a，cost for labor=2a
profit+cost for labor+cost for m=500000而且profit>cost for labor
可得 profit +3a=500000  推出a=（500000-profit)/3    又因为 profit>2a
所以p>[2（500000-P）]/3  化简可得 p>20,000