What formula would you use when there is inflation and you must find the price of a product in the past several years? But you are given, the present value, the interest rate (r), and t.

To find the price of a product in the past several years when there is inflation, you can use the formula for the future value of an investment adjusted for inflation. The formula is:

FV = PV * (1 + r)^t

Where:
FV = Future Value (price in the present)
PV = Present Value (price in the past)
r = Interest rate (in decimal form)
t = Number of years

Now, to find the price of the product in the past several years, you would rearrange the formula to solve for PV (Present Value). The rearranged formula would be:

PV = FV / (1 + r)^t

By substituting the given values of FV (present value), r (interest rate), and t (number of years), you can calculate the price of the product in the past several years.