Question

The sale price S (in dollars) of an item is given by the formula S=L-rL, where L is the list price (in dollars) and r is the discount rate (in decimal form).Solve the equation for r.

Answer 1

ANSWER

$r=1-(\frac{S}{L})$

EXPLANATION

Given;

$S=L-rL$

To make r the subject of formula, flip the equation

$rL=L-S$

Divide both sides by L;

$\begin{gathered} \frac{rL}{L}=\frac{L-S}{L} \\ r=\frac{L-S}{L} \\ =\frac{L}{L}-\frac{S}{L} \\ =1-\frac{S}{L} \end{gathered}$