Price per unit:
Shoes: $75.99
Socks: $5.99
If he bought x shoes and y socks, the total price for each item is:
[tex]\begin{gathered} \text{Shoes}\colon75.99x \\ \text{Socks}\colon5.99y \end{gathered}[/tex]We know that he spent $169.95 before tax, corresponding to the sum of the total price for each item. Then, the equation that models his purchase is:
[tex]75.99x+5.99y=169.95[/tex]