hello guys, i need assistance in computing this

Build a function retirement_age(PMT, i, FV, start_age) that calculates the (whole) age at which your customer can retire, if they:

• invest an amount, PMT at the END of every YEAR (with the first payment made exactly one year from now),
• at an interest rate of i% per year, compounded annually,
• they require an amount of AT LEAST FV in order to be able to afford retirement and
• they just turned start_age years old.