Question

Sierra left $4.50 as a tip for a waiter. THis was 18% of the bull before the tip, How much was her total bill before the tip?

Answer 1

let's say the bill without the tip is "x" amount, so that'd be the 100% of the bill, but we also know that 4.50 is the 18% of "x".

so if 4.50 is the 18% of "x", how much is "x"?

$\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 4.50&18\\ x&100 \end{array}\implies \cfrac{4.5}{x}=\cfrac{18}{100}\implies 450=18x \\\\\\ \cfrac{450}{18}=x\implies 25=x$