Divide 45 by 5. The answer would be 9.
The measured data is
x=[10.56, 9.52, 9.73, 9.80, 9.78, 10.91].
Calculate the mean.
m = (10.56+9.52+9.73+9.80+9.78+10.91)/6 = 10.05
Calculate the deviations from the mean.
k = x - m
= [0.51, -0.53, -0.32, -0.25, -0.27, 0.86]
Calculate the absolute deviation from the mean.

Answer: 0
The discount price will be the same either way. (The commutative property)
20 percent of $89.00= 17.80$
$89.00 - ($5.00 x $17.80) = $66.20
$89.00 - ($17.80 x $5.00) = $66.20