business is offered the opportunity to invest a series of monthly payments into a merchant bank, w the first such payment to take place in exactly $8$ months time and the last in exactly $32$ years time.The merchant bank takes a fixed percentage of each payment to cover its expenses, and promises to p the business a lump sum of R$12596535$ in $35$ years time.If the interest rate earned on all the payments is $18\%$ per annum convertible monthly. find the fixed percentage of each payment taken by the bank for its expenses.