[求助] 两道 DS 题

1.       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

这种文字转换题是我的弱项，
        答案选择C，
        烦请大家给我解释一下，谢谢

2.       A contractor combined X tons of a gravel mixture that contains 10 percent gravel G, by weight, with Y tons of a mixture that contains 2 percent gravel G, by weight, to produce Z tons of a mixture that was 5 percent gravel G, by weight. What is the value of X?

(1)    Y=10

(2)    Z=16

答案选择D，
        我列了一个等式，应该是必须Y,Z两个量知道了才行，不知道为什么是D。谢谢大家的解释

yunlinli，thank you very much, your explanation is very clear.

第二题我自己根据最终混合物的combination情况列了一个有关X,Y,Z的等式，因为没有Y和Z之间的关系，所以答案最后选择D， 我实在不能理解。

大牛们，烦请解释一下吧

知道的大牛们解释一下吧，谢谢