prep60求解~ 62求解~

promiselu

60.    7189-!-item-!-187;#058&005472
Rates for having a manuscript typed at a certain typing service are $5 per page for the first time a page is typed and $3 per page each time a page is revised.  If a certain manuscript has 100 pages, of which 40 were revised only once, 10 were revised twice, and the rest required no revisions, what was the total cost of having the manuscript typed? 题目啥意思

(A) $430
(B) $620
(C) $650
(D) $680
(E) $770

我算50*5+40*3+10*3*3=460， 没这个答案。。然后又试100*5+40*3+10*3*3还是没有。。。。。
关键是看不懂题目是什么意思

62.    7564-!-item-!-187;#058&005577
Alice's take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month.  The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save.  If all the money that she saved last year was from her take-home pay, what fraction of her take-home pay did she save each month?

(A) 1/2
(B) 1/3
(C) 1/4
(D) 1/5
(E) 1/6
这题的问题真绕啊~
设每月赚A，存X比例，未存1-x
12Ax=3xA(1-x)  x=-3?....~~~`  怎么可能是负数。。。可能我方程列错了
求解~

fangpyj8906

60 . Lz貌似漏掉了一个东东，100pages肯定是都经过了第一次type,然后才有40pages revised once,10pages revised twice，因此应该是100*5+40*3+10*3*2(这10张修订了两次，每次3刀）结果为680

promiselu

62理解错了，应该是12Ax=3A(1-x)  
x=1/5