Let the cost of pair of shoes is x.
So we can get price s by adding cost and sales tax.
Sales tax = 5% of cost
= [tex]\frac{5*x}{100} = \frac{x}{20} [/tex]
So the price of pair of shoes is modeled as given below
[tex]s = x + \frac{x}{20} [/tex]
[tex]s = \frac{20x + x}{20} [/tex]
[tex]s = \frac{21x}{20} [/tex]