Answer :
We can setup a simple ratio and solve this problem.
We can say:
2/7 miles to 2/5 hr MEANS how many miles per 1 hour???
Let's call the unknown "x", so we can write the ratio as:
[tex]\frac{\frac{2}{7}}{\frac{2}{5}}=\frac{x}{1}[/tex]Now, we cross multiply and solve for x:
[tex]\begin{gathered} \frac{\frac{2}{7}}{\frac{2}{5}}=\frac{x}{1} \\ x\cdot\frac{2}{5}=1\cdot\frac{2}{7} \\ \frac{2}{5}x=\frac{2}{7} \\ x=\frac{\frac{2}{7}}{\frac{2}{5}} \\ x=\frac{2}{7}\cdot\frac{5}{2} \\ x=\frac{5}{7} \end{gathered}[/tex]So, unit rate is 5/7 miles per hour.