John pays $2500 at time 0 in order to receive $400 at the end of each year for 7 years with the first payment at the end of the first year. He also receives a lump sum of $1000 at time 8 years. Find the annual interest rate that he earns on his money.

The given answer is 9.0% but I don't know how to do it.

Calculations using excel works too.