Please help !!!

Determine the present worth of a geometric gradient series with a cash flow of $50,000 in year 1 and increases of 6% each year through year 8. The interest rate is 10% per year. Determine the difference in the present worth values of the following two commodity contracts at an interest rate of 8% per year. Contract 1 has a cost of $10,000 in year 1; costs will escalate at a rate of 4% per year for 10 years. Contract 2 has the same cost in year 1, but costs will escalate at 6% per year for 11 years