Question

Flying with the wind, a small plane flew 240 mi in 2 h. Against the wind, the plane could fly only 210 mi in the same amount of time. Find the rate of the plane in calm air and the rate of the wind.

Answer 1

2(p+w)=240

p+w=120

w=120-p, we will use this value for w below...

2(p-w)=210

p-w=105, now use the w from earlier...

p-120+p=105

2p-120=105

2p=225

p=112.5 mph  (and wind is 7.5 mph)