What is the average of 15 23 13 and 29?

To find the average of the numbers 15, 23, 13, and 29, first add them together: 15 + 23 + 13 + 29 = 80. Then, divide the sum by the number of values, which is 4: 80 ÷ 4 = 20. Therefore, the average is 20.