Calculate the difference between purchase and sales costs:
$52,000 - $42,000 = $10,000
Calculate what fraction of $52,000 is $10,000:
[tex]\dfrac{\$10,000}{\$52,000}=\dfrac{10}{52}=\dfrac{5}{26}[/tex]
Transform it to the percent:
[tex]\dfrac{5}{26}=\dfrac{5}{26}\cdot100\%=\dfrac{500}{26}\%\approx19\%[/tex]
Answer: A. 19%
