Question 211531
d=rt
1000=4r
r=1000/4
r=250 mph. plane speed with the wind.
500=4r
r=500/4
r=125 mph. plane speed against the wind.
(250-125)/2=125/2=62.5 mph. was the wind speed.
250-62.5=187.5 was the speed of the plane in calm air.
125+62.5=187.5 ditto.