Question 469312
plane speed		x	mph				
wind speed		50	mph				
..							
against wind   		x	-	50	mph		
with wind  		x   	+	50	mph		
							
Distance against 	wind	200					
Distance with 	wind	400					
Time = same							
200	/(x-	50	)=	400	/(x+	50	)
200	*(x+	50	)=	400	*(x-	50	)
200	x  	+	10000	=	400	x	-20000
400	x  	-200	x   	=	20000	+	10000
200	x  	=	30000				
/	200						
	x=	150	mph