The item was sold for $225 and the original cost of the item is unknown. The mark up of the item is 80%. The original cost can be solved below
let
cost price = x
[tex]\begin{gathered} \text{selling price=\$225} \\ \text{ cost price=?} \\ \text{ mark up=80\%}=\frac{80}{100} \\ profit=\frac{80}{100}\times x=0.8x \\ 225=0.8x+x \\ 225=1.8x \\ x=\frac{225}{1.8} \\ x=\text{ \$125} \end{gathered}[/tex]