First, add all three numbers together. Then, divide that number by three, because there were three numbers to begin with. If you put this into a calculator, you will get 4.33333333... because 1/3 is equal to 0.333333333. This is useful to know because then when you get 0.6666666 you know that it is 2/3. Anyway, your answer is 4 1/3.
