from the question given, we have
1. cost of shoes
2. percentage of sale tax
3. cost of laces
let's find 7% in $50 and also $1
the sales tax in the shoes are
[tex]\begin{gathered} 7\text{ \% in 50} \\ \frac{7}{100}=\frac{x}{50} \\ 100x=7\times50 \\ 100x=350 \\ \text{divide both sides by 100} \\ \frac{100x}{100}=\frac{350}{100} \\ x=3.5 \end{gathered}[/tex]