You are about to invest your $10,000 in three different funds. Fund 1 offers an expected rate of return of 4%. Fund 2 offers an expected rate of return of 8%. However, your income tax is much higher in Fund 2 and it was recommended to invest in Fund 1 at least three times more than Fund 2. Fund 3 offers an expected rate of return of 10%. Fund 3 is tax-free with a maximum limit of $2000. Formulate this problem to maximize your annual return.