Question 669907
Tugboat	speed	=x	mph					
current     	speed	=y	mph					
against  	current     	10	hours					
with	current     	5	hours					
								
Distance against 		100	miles	distance with wind 		100	miles	
t=d/r	against	wind		-				
100	/	(	x	y	y	)=	10	
10	(	x	-	y	)	=	100	
10	x	-	10	y	=	100	....................1	
								
100	/	(	x	y	y	)=	5	
5	(	x	+	y	)	=	100	
5	x	+	5	y	=	100	...............2	
Multiply (1) by	1							
Multiply (2) by	2							
we get				y				
10	x	+	-10	y	=	100		
10	x	+	10		=	200		
20	x	=	300					
/	20							
x	=	15	mph					
								
plug value of x in (1)				y				
10	x		-10	y	=	100		
150			-10	-150	=	100		
-10	y	=	100					
-10	y	=	-50	mph				
	y	=	5					
Tugboat	speed	15	mph					
current     	speed	5	mph					
								
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