求教小蓝上371的过程

norlanzhang

371. John and Mary were each paid x dollars in advance to do a certain job together, John worked for 10hours and Mary worked for 2 hours less than John. If Mary gave John y dollars of her payment so that they would have received the same hourly wage, what was the dollar amount, in terms of y, that John was paid in advance?
A.4y   B. 5y  C. 6y  D. 8y  E. 9y

Wanted700

John 10hours   X
Mary 8hours     X

x/8-x/10=Y, X=40Y, so hour wage = 40Y/10hour=4Y/hour

fancifully1234

我的思路好像不一样。这个题目的意思是，本来，John和Mary都是X$,只是一个10小时，一个8小时。
然后John给了MaryY$。。。后来他们的hourly pay相同?
这样的话，(X-Y)/8=(X+Y)/10 ..最后算出来 X=9Y

不知道，我的思路对吧。
没做过小蓝，标准答案是？