Question 771159
Plane  	speed	=x	mph						
wind   	speed	=y	mph						
against 	wind   	4	hours						
with 	wind   	3	hours						
									
Distance with	wind   	2400	miles		distance against	wind   	2400		
t=d/r	against	wind   	(x-y)						
2400.00	/	(	x	-	y	)=	4.00		
									
4.00	x	-	-4.00	y	=	2400.00	....................1		
with	wind   	(x+y)							
2400.00	/	(	x	+	y	)=	3.00		
3.00	(	x	+	y	)	=	2400.00		
3.00	x	+	3.00	y	=	2400.00	...............2		
Multiply (1) by	3.00								
Multiply (2) by	4.00								
we get									
12.00	x	+	-12.00	y	=	7200.00			
12.00	x	+	12.00	y	=	9600.00			
24.00	x	=	16800.00						
/	24.00								
x	=	700	mph						
									
plug value of x in (1)				y					
4	x		-4	y	=	2400			
2800			-4	-2800	=	2400			
-4	y	=	2400						
-4	y	=	-400	mph					
	y	=	100						
Plane  	700	mph							
wind   	100	mph							
									
CHECK									
x+y=	800								
X-y=	600			+					
2400.00	/	(	800.00			)=	3		
2400	/	(	600	)		=	4