we write the relation
1/8in is 12 miles, how much miles is 4 inches?
[tex]\begin{gathered} \frac{1}{8}\longrightarrow12 \\ \\ 4\longrightarrow x \end{gathered}[/tex]where x is the number of miles to 4 inches
we can use cross multiplication to find x
multiply diagonal numbers (4 and 12) and dividing between 1/8 we obtain the value of x
[tex]\begin{gathered} x=\frac{4\times12}{\frac{1}{8}} \\ \\ x=6 \end{gathered}[/tex]then the distance between two cities is 6 miles