What is average 21 6 and 9?

To find the average of the numbers 21, 6, and 9, first add them together: 21 + 6 + 9 = 36. Then, divide the sum by the number of values, which is 3: 36 ÷ 3 = 12. Therefore, the average of 21, 6, and 9 is 12.