Question

An airplane can fly 625 miles with the wind in the same amount of time as it can fly 425 miles against the wind. If the wind speed is 50 mph, find the speed of the plane in still air. (Round your answer to the nearest whole number.)

Answer 1

R=rate
d=distance
t=time
c=current
d=(R+C)(t)
625=(R+50)(t)
425+(R-50)(t)
625/(R+50)=t
425/(R-50)=t
equate these two.
625/(R+50)=425/(R-50)
cross multiply
625R-31250=425R+21250
625R-425R=21250+31250
200R=52500
R=262.5
R=263 mi/hr.

check:

625=(263+50)t
t=2hrs.
425=(263-50)t
t=2hrs.

Ergo, the rate of plane in still air is 263 mi/hr.