Question 46652
Finally, a question about aeroplanes!

Let the windspeed be called "w" and the time taken be called "t".
We know that the time taken for the plane to cover a certain distance is equal to its speed divided by that distance.
We can now write two equations:
{{{(180+w)/7=t}}} (with the wind)
{{{(180-w)/5=t}}} (against the wind)
Notice how both equations are equal to "t". This means we can say:
{{{(180+w)/7=(180-w)/5}}}
Now rearrange to find "w":
{{{5(180+w)=7(180-w)}}}
{{{900+5w=1260-7w}}}
{{{12w=360}}}
{{{w=360/12=30}}}
So the wind speed is 30mph.
I hope this helps,
Adam.
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