Find the mean absolute deviation of the set of data 16, 20, 24, 25, 28, 29, 31 and 35

1. find the mean of the numbers - I had 26

2, take the deviaton of each of your data value
i.e.
26-16 = 10
26-20 = 6
...
26-35 = -9

3. take the absolute values of the above deviations
4. find the mean of those positive numbers

actually if you have Excel, there is a function AVEDEV(....) that will do this for you

enter 16, 20, ... 35 into
cells A1, A2, ... A9
in cell B1 put = AVEDEV(A1:A9)

you should get the result in B1