Question 800877
boat   	speed	=x	mph						
current     	speed	=y	mph						
against  	current     	5	hours						
with	current     	2	hours						
									
Distance against 		20	miles	distance with 		20	miles		
t=d/r	against	current     		-					
20.00	/	(	x	-	y	)=	5.00		
5.00	(	x	-	y	)	=	2.00		
5.00	x	-	5.00	y	=	20.00	....................1		
									
20.00	/	(	x	+	y	)=	2.00		
2.00	(	x	+	y	)	=	20.00		
2.00	x	+	2.00	y	=	20.00	...............2		
Multiply (1) by	2.00								
Multiply (2) by	5.00								
we get									
10.00	x	+	-10.00	y	=	40.00			
10.00	x	+	10.00	y	=	100.00			
20.00	x	=	140.00						
/	20.00								
x	=	7.00	mph						
									
plug value of x in (1)				y					
5.00	x		-5.00	y	=	20.00			
35.00			-5.00	-35.00	=	20.00			
-5.00	y	=	20.00						
-5.00	y	=	-15.00	mph					
	y	=	3.00						
boat   	speed	7.00	mph						
current     	speed	3.00	mph						
									
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