Question 535026
plane  	speed	=x	mph					
wind speed	speed	=y	mph					
against current x-y		6.00	hours					
With current x+y		4.00	hours					
								
Distance = same=		624	miles					
t=d/r								
624	/	(	x	-	y	)=	6.00	
6	(	x	-	y	)	=	624.00	
6	x		-6	y	=	624	....................1	
624	/	(	x	+	y	)=	4.00	
4.00	(	x	+	y	)	=	624	
4.00	x	+	4.00	y	=	624	...............2	
Multiply (1) by 	2.00							
Multiply (2) by	3.00							
we get								
12	x	+	-12	y	=	1248		
12	x	+	12	y	=	1872		
24	x	=	3120					
/	24							
x 	=	130	mph					
								
plug value of x in (1)								
6	x		-6	y	=	624		
780			-6	y	=	624		
-6	y	=	624	-780				
-6	y	=	-156					
	y	=	26	mph				
	plane  	130	mph					
	wind speed	26	mph					
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