请帮忙解答 谢谢！！
4. If (x+1/x) / (1+1/x) = 99 then Find value of (x-1/x)/(1+1/x) = ? 不会。。。。
5. Given that the perimeter of rectangle A > perimeter of rectangle B
Col a: Area of rectangle A
Col b: Area of rectangle B 是不是 D不确定？？
8.
What is the circumference of the circle? 10pi?
11. There are 15 employees in company, the mean of salaries of the least paid seven employees is given and the mean of the salaries of the highest paid employees is given
Col A: the median of the salaries of the 15 employees.
Col B: some value very close to the mean of the above given means was given. D不确定？？
14. If ab is not equal not 0, a is not equal to b, & a/b = b/a
Col A: a+b
Col b: 0 D不确定？？
