Question

there is a 20% discount with a set of tires in normally sells for $368. How much will be tires cost after the discount?

Answer 1

same as before, if we take 368 to be the 100%, how much is 20% off that?

$\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 368&100\\ d&20 \end{array}\implies \cfrac{368}{d}=\cfrac{100}{20}\implies \cfrac{368\cdot 20}{100}=d$

so, the discount is that much, thus, the discounted price is then 368 - d.