You wish to retire in 20 years, at which time you want to have accumulated enough money to receive an annual annuity of $12,000 for 25 years after retirement. During the period before retirement you can earn 8 percent annually, while after retirement you can earn 10 percent on your money. What annual contributions to the retirement fund will allow you to receive the $12,000 annuity? **Please explain this one as detailed as possible, I know questions like this have been answered already but not clearly enough for me, Thank you!