The maintenance and operations costs for a piece of equipment are estimated to be $400 the first month and increase by $20 per month over the equipment's 3 year life. For budgeting purposes, the owner wants to set aside a uniform amount each month to cover the maintenance and operations costs of the equipment. If the owner can invest at 8% per year, compounded monthly, what amount should he invest each month? Express your answer in $ to the nearest $10.