so, the scale is on the map is 3/10 inch equals to an actual 7/8 miles, then how many inches are there in 1 mile?
[tex]\bf \begin{array}{ccll}
inches&miles\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
\frac{3}{10}&\frac{7}{8}\\\\
x&1
\end{array}\implies \cfrac{\quad \frac{3}{10}\quad }{x}=\cfrac{\quad \frac{7}{8}\quad }{1}\implies \cfrac{\quad \frac{3}{10}\quad }{\frac{x}{1}}=\cfrac{\quad \frac{7}{8}\quad }{\frac{1}{1}}[/tex]
[tex]\bf \cfrac{3}{10}\cdot \cfrac{1}{x}=\cfrac{7}{8}\cdot \cfrac{1}{1}\implies \cfrac{3}{10x}=\cfrac{7}{8}\implies 24=70x\implies \cfrac{24}{70}=x\implies \stackrel{inches}{\cfrac{12}{35}=x}[/tex]
