You are making plans for your retirement. You have just turned 30 and want to retire on your 65^thbirthday. Once retired, you plan to move to a tax-free Caribbean state, where you believe you can live comfortably on $10,000 per month. Your first payment of $10,000 will occur when you retire at age 65, and you will receive your last instalment from your retirement fund one month before your 85^thbirthday. On your 85^thbirthday, you intend to move back to Canada and freeload off your kids until you die.

Your current salary is $60,000 per year, or $5,000 per month. Your personal tax rate is approximately 25%. You estimate that you can earn an average return of 10% APR compounded annually on any money you invest over the next 60 years. You will make your first deposit one month from now and your last deposit on your 65^thbirthday. To ensure that you are able to achieve your retirement objective, what percentage of your after-tax monthly income must you save?

I have figured this out :

Amount needed 2390000

After Tax Income45000

Per Month 3750

PV 0

FV 2390000

Interest 10%

I am confused about the 10% investment for the next 60 years and the compounding interest.