Find the percent of increase from 1.5 inches to 6 inches.

well, from 1.5 to 6 is a 4.5 difference.

now, if we take 1.5 to be the 100%, what is 4.5 off of it in percentage?

[tex]\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 1.5&100\\ 4.5&p \end{array}\implies \cfrac{1.5}{4.5}=\cfrac{100}{p}\implies p=\cfrac{4.5\cdot 100}{1.5}[/tex]