Suppose x is the speed of the airplane.

We also need to know that d=rt so `t=d/r`

So the rate with the wind is x+20, and the rate against is x-20 so using the above formula for time we have

` 600/(x+20)=500/(x-20)` cross multiplying we get

600(x-20) = 500(x+20) distributing

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Suppose x is the speed of the airplane.

We also need to know that d=rt so `t=d/r`

So the rate with the wind is x+20, and the rate against is x-20 so using the above formula for time we have

` 600/(x+20)=500/(x-20)` cross multiplying we get

600(x-20) = 500(x+20) distributing

600x - 12000 = 500x + 10000 Subtracting 500x and adding 12000 gives us

100x = 22000 solving for x

x = 220km/hr our answer, which is a reasonable rate for a plane.

We could check,

time with the wind = 600/(220+20) = 600/240 = 2.5 hours

time against the wind = 500/(220-20) = 500/200 = 2.5 hours

So the answer is 220km/hr