Question

Item 20 A store pays $40 for a scanner. The store sells the scanner for $90. Your classmate says that the markup is 225% because $90/$40=2.25. Is your classmate correct?

Answer 1

if we take 40 to be the 100%, what is 90 off of it in percentage?

$\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 40&100\\ 90&x \end{array}\implies \cfrac{40}{90}=\cfrac{100}{x}\implies x=\cfrac{90\cdot 100}{40}\implies x=\stackrel{\%}{225}$

well, it turns out the 90 is indeed the 225% of 40.

however, markup is the "added amount to the original price", now, the added amount wasn't 90, was 50 bucks, and that is NOT 225% of 40, is actually 125% added, and therefore the markup rate.