Please help i dont know how to do this and i have a test coming up

Trish receives $450 on the first of each month. josh receives $450 on the last day of each month. both trish and josh will receive payments for next four years. at a discount rate of 9.5 percent, what is the difference in the present value of these two sets of payments?

This assignment is past the original due date o this data is from a sample. calculate the mean, standard deviation, and variance 16.7 11.1 46.7 14.8 13.3 16.6 18.5 47.3 42,8 show the following answers to 2 decimal places. sample mean- sample standard deviation ( use the standard deviation above for your calculation.) sample variance ooops- now you discover that the data was actually from a population! so now you must give the population standard deviation.

Three problems for 50 ! 1- -3t=99 2- 1/6k=-11 3- 4 1/2 +q=9 1/2 show work thx s !