Start by writing the sales price as function
[tex]y=k(1-x)[/tex]in which y is the sales price, k is the original price and x is the discount percentage in decimal form.
[tex]y=100\cdot(1-0.1)[/tex]solve for y
[tex]\begin{gathered} y=100\cdot(1-0.1) \\ y=100\cdot0.9 \\ y=90 \end{gathered}[/tex]The sales price will be $90
