Question 768080
Boat speed	speed	=x	kph					
current     	speed	=y	kph					
against  	current     	6	hours					
with	current     	1.5	hours					
								
Distance against 		12	miles	distance with 		12	miles	
t=d/r	against	current     		-				
12	/	(	x	-	y	)=	6	
6	(	x	-	y	)	=	12	
6	x	-	6	y	=	12	....................1	
								
12	/	(	x	+	y	)=	1.50	
1.50	(	x	+	y	)	=	12	
1.50	x	+	1.50	y	=	12	...............2	
Multiply (1) by	1    							
Multiply (2) by	4							
we get								
6.00	x	+	-6	y	=	12		
6.00	x	+	6	y	=	48		
12	x	=	60					
/	12							
x	=	5	kph					
								
plug value of x in (1)								
6	x		-6	y	=	12		
30			-6	y	=	12		
-6	y	=	12	-30				
-6	y	=	-18	mph				
	y	=	3					
Boat speed	speed	5	kph					
current     	speed	3	kph					
								
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