Asap i cant seem to get out of this question its

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?

Im literally having a mental breakdown

Find the unit rate for: 75% high-fiber chimp food to 25% high -protein chimp food.