Question 539550
Plane  	speed	=x	mph					
Wind  	speed	=y	mph					
against wind x-y		4.00	hours					
with wind x+y		3.00	hours					
								
Distance = same=		1200	miles					
t=d/r								
1200	/	(	x	-	y	)=	4.00	
4	(	x	-	y	)	=	1,200.00	
4	x		-4	y	=	1200	....................1	
1200	/	(	x	+	y	)=	3.00	
3.00	(	x	+	y	)	=	1200	
3.00	x	+	3.00	y	=	1200	...............2	
Multiply (1) by 	3.00							
Multiply (2) by	4.00							
we get								
12	x	+	-12	y	=	3600		
12	x	+	12	y	=	4800		
24	x	=	8400					
/	24							
x 	=	350	mph					
								
plug value of x in (1)								
4	x		-4	y	=	1200		
1400			-4	y	=	1200		
-4	y	=	1200	-1400				
-4	y	=	-200					
	y	=	50	mph				
	Plane  	350	mph					
	Wind  	50	mph					

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