Answer :
[tex]\begin{gathered} \text{if 3 cm correspond to 15 miles, } \\ 1\text{ cm correspond to 15/3 = 5 miles. } \\ \text{thus 8 cm corresponds to } \\ 8\cdot5=40\text{ miles} \\ \\ \text{thus, the next town is 40 miles away} \end{gathered}[/tex]