Answer:
135 mph
Explanation:
Let the speed of plane in sill water is x mph
It is given that speed of wind is 10 mph
So the speed of plane in the direction of wind speed =x+10
So the speed of plane against the direction of wind speed =x-10
It is given that plane takes same time in both with the wind speed and against the wind speed so [tex]\frac{435}{x+10}=\frac{375}{x-10}[/tex]
60x=8100
x=135 mph
So the speed of plane in still water is 135 mph