Anna has been saving $450 in her retirement account each month for the last 20 years and plans to continue contributing $450 each month for the next 20 years. Her account has been earning a 9 percent annual interest rate and she expects to earn the same rate for the next 20 years. Her twin brother, Anthony, has not saved anything for the last 20 years. Due to sibling rivalry, he wants to have as much as Ana is expected to have at the end of 20 years. If Anthony expects to earn the same annual interest rate as Anna, how much must Anthony save each month to achieve his goal?