#### Explanation:

Let $g$ represent the value of good sold and $t$ represent the tax collected on the goods sold.

We are told:
$\textcolor{w h i t e}{\text{XXX}} g + t = 1272$
and
$\textcolor{w h i t e}{\text{XXX}} t = \frac{6}{100} g$

Therefore
$\textcolor{w h i t e}{\text{XXX}} g + \frac{6}{100} g = 1272$

$\textcolor{w h i t e}{\text{XXX}} 106 g = 127200$

$\textcolor{w h i t e}{\text{XXX}} g = \frac{127200}{106} = 1200$

and since $g + t = 1272$
$\textcolor{w h i t e}{\text{XXX}} t = 72$