Answer
See below.
Work Step by Step
a) The mean of $n$ numbers is the sum of the numbers divided by $n$.
Hence the mean: $\frac{146+153+155+160+161}{5}=155$
b) The deviation is the difference of the data item and the mean.
Hence here the deviations: $146-155=-9,153-155=-2,155-155=0,160-155=5,161-155=6$
c) The sums of the deviations: $-9-2+0+5+6=11$
