求助Prep~！马上一战了，还有很多很小白的问题啊！！急问！

我4小花痴

昨天做了下prep
分数巨悲剧啊。。。。
最近LZ很苦逼
做什么都不顺
经常倒霉啊！！

好了，放小白题。。。。
数学一向很差。。。大家轻拍。。。
1、If n is  amultiple of 5 and n=p^2*q,where p and q are prime numbers,which of the following must be a multiple of 25?
2、If x^4+y^4=100,then the greatest possible value of x is between?答案是6~9
3、If n is a positive integer and r is the remainder when 4+7n is divided by 3,what is the value of r?
4、What is the ten digit of the positive interger r?
   (1)The ten digit of r/10 is 3
   (2)The hundreds digit of 10r is 6
5、Six countries in a certain region sent a total of 75 representatives to a international congress,and no two countries sent the same number of representative.Of the 6 countries ,if country A sent the second greatest number of r ,did country Asend at least 10 representatives?

我4小花痴

肿磨没有人理啊。。。自己顶