Catherine Dohanyos plans to retire in 15 years . She will make 15 years of monthly contributions to her retirement account . One month after her last contribution , she will begin the first of 10 years of withdrawals . She wants to withdraw $ 2900 per month . How large must her monthly contributions be in order to accomplish her goal if the account earns interest of 7.7 % compounded monthly for the duration of her contributions and the 120 months of withdrawals ?

The amount of her monthly contributions must be?