Question

By what percent did the price change, if… a the price was $100 and now it is $250?

Answer 1

It had a 150% increase in price

100* 1.5 = 150
150+100 = 250

Answer 2

Well, if we take $100 to be the 100%, and then it went up by $150, how much is $150 off of it in percentage?

$\bf \begin{array}{ccll} \ &\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 100&100\\ 150&x \end{array}\implies \cfrac{100}{150}=\cfrac{100}{x}\implies x=\cfrac{150\cdot 100}{100}$