Please do step by step and explain how you did it. I know I could find the answer, but I want to know how to do it so that I can do it on future problems. Thank you very much!!

12 Three years ago, you invested in a retirement account. The account had three holdings, with annual returns as shown below. What was the average annual return on the portfolio over this time? Annual Initial Dividend (paid to Return Return Return Stock Investment you on your Year 1 Year 2 Year 3 investment) General Motors $10,000 $200 +6% +4% +5% General Electric $40,000 $800 +7% General Dynamics $15,000 $300 +7% +5% +10% -3% -8%