Given:
Tim bought a pair of shoes for $100 on 20% down.
Let 'x' be the original price of the shoes.
Percentage of amount paid for the shoes is 80%
[tex]100=x\times\frac{80}{100}[/tex][tex]100\times\frac{100}{80}=x[/tex][tex]x=\frac{10000}{80}[/tex][tex]x=125[/tex]
Therefore, the original price of the shoes is $125
