Answer-
The speed of wind is 13 mph
Solution-
We know that,
[tex]Speed =\frac{Distance}{time}[/tex]
⇒ [tex]Time=\frac{Distance}{Speed}[/tex]
Let's assume, W = speed of wind
39 + W = speed with the wind
39 - W = speed against the wind
Time taken by him to travel with the wind [tex]=\frac{26}{39+W}[/tex]
Time taken by him to travel against the wind [tex]=\frac{13}{39-W}[/tex]
∴ As he takes same time for both the cases
⇒ [tex]\frac{26}{39+W} = \frac{13}{39-W}[/tex]
⇒ 78 - 2W = 39 + W
⇒ 3W = 39
⇒ W = 13 mph
