You are 22 years old, have saved up $40,000, and have a goal of being a millionaire

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Question:

You are 22 years old, have saved up $40,000, and have a goal of being a millionaire by age 50.You intend to make monthly contributions into your investment account each month. You estimate you can earn 7% compounded quarterly on the investment account. How much must you put into that account monthly to reach your goal? Please show work.