请教几道八月 jj

chenbo

67. 某人有bookcase, arrange 10 books per shelf and no books left. If he acquired 10 additional books, and arrange 12 books per shelf, no books left. Ask how many books he has before acquiring the addition 10 books
A before acquiring, his books less than 96
B before acquiring, his books more than 24
参考答案：a
设架子有x个,10x+10=12x,得x=5，书的数量不是已经可以确定了吗？和条件有什么关系？
92. 卖汽车，7天中分别卖了，3，2，4，5，6辆（数字顺序记得不是很清楚了）；第7天卖的数量是3，5，4中的一个，问7天共卖的数量的平均值有可能是第7天卖的数量的那一个。
I， 5
II， 3
III， 4
参考答案：
这题什么意思，怎么做？
108. M能被3整除, 问M是否有两个质数因子
1.  M/3能被3除
2.  M/3 可被两个不同的质数整除.
参考答案：b
184. a company increases its costs/labor charges from $50/hour to $60/hour and enhances its parts charges by 8%. a certain job requires 1.5 hours of labor charges and parts charges, and the parts charges before change were $125/hour. what percent will the total charges for this job increase?
参考答案：1/8
思路：[1.5(60-50)+125*0.08]/(50*1.5+125)
为什么125不乘以1。5，题中不是$125/hour.吗？
246. 4 teams debate to other 6teams. one team can debate at most once, the order is irrelevant, total detates between these teams
参考答案：24

chenbo

各位帮帮忙吧，我就要考，数学却其差，55555