At the beginning there is 5000 in an account. Thereafter, 2000 is paid in at the end of each year for a year, with annual compound interest at an interest rate of 3% p.a. being agreed. After the a year no more payments are made and for the following b years the account bears compound interest annually at an interest rate of 4% p.a. How high is the account balance after a + b years? (For a and b, take integer values from the set {3,4, ..., 12} such that a