Question

In the past you paid $800per month to rent your apartment. You now pay $900per month for your rent. What is the percent increase in your rent?

Answer 1

so, if we take 800 as the 100%, the increase is 900-800 or 100, what is 100 in percentage of 800?

well
`\bf \begin{array}{ccllll} amount&\%\\ \textendash\textendash\textendash\textendash\textendash\textendash&\textendash\textendash\textendash\textendash\textendash\textendash\\ 800&100\\ 100&x \end{array}\implies \cfrac{800}{100}=\cfrac{100}{x}`

solve for "x"