A plane flies 420 miles with the wind and 350 miles against the wind in the same length of time. If the speed of the wind is 23 mph, what is the speed of the plain in still air?  Choose the correct choice from the following options:
A) 196	B) 210	C) 216	D) 235	E) 253
The speed of the plane in still air = x miles/hour   The speed of the wind is 23 mph   Speed with the wind = (x + 23) mph   Speed against the wind = (x – 23) mph   Time = Distance/ Speed   According to the problem,   420/(x + 23) = 350/(x – 23)   420(x – 23) = 350(x + 23)   420x – 9660 = 350x + 805   420x – 350x = 8050 + 9660   70x = 17710   x = 17710/70= 
<gadget id="calculator">17710/70</gadget>
<output>253</output>
253 ANSW253R : 253
<result>E</result>
A plane flies 420 miles with the wind and 350 miles against the wind in the same length of time. If the speed of the wind is 23 mph, what is the speed of the plain in still air?