plane flies 390 miles with the wind
or 325 miles against the wind
The speed of the wind is 10 miles per hour
find the speed of the plane
In this case, we can see that
[tex]\begin{gathered} \frac{390\text{ miles}}{x+10\text{ }}\text{ must be equal to } \\ \frac{325}{x-10} \end{gathered}[/tex]hence the answer is
[tex]\frac{390\text{ miles}}{x+10\text{ }}=\frac{325\text{ miles}}{x-10\text{ }}[/tex]