Please help me in the following questions. Please show all work with formula!

1. A postal worker can sort a stack of mail in 40 minutes. How many stacks could the worker sort in 3 hours and 35 minutes.
2. Build up the denominator:? / 10x^3-2x^2 = 1 / 5x-1
3. The sum of the reciprocal of two consecutive odd integers is 20/99. Find the two integers.
4. Find the excluded values of: 10????^2+23????5 / 5????^251????+10