Computing the present value of a series of cash flows

Given loan interest rate = 8%

bank saving interest rate = 5%

Given the following yearly cash flows with zero initial capital:

$ -1,000 $ 900 $ 800 $ -1,200 $ 700

My teacher gives the answer of the future value of these cash flows at the beginning of the fifth year:

(((-1000*1.08 + 900) 1.08 + 800) 1.05 -1200 )*1.08 + 700

= 90.7504

Now, he asked me to compute the present value of $ 90.7504.

I really don't know how to do since different loan interest rate and saving interest rate are given.

He also said that it is incorrect to simply discount $ 90.7504 by (1+5%)^4

Can anyone help?(Angry)