Question 539568
Whale	speed	=x	mph					
current    	speed	=y	mph					
against current , x-y		2	hours					
with current , x+y		1.5	hours					
								
Distance = same=		60	miles					
t=d/r								
60	/	(	x	-	y	)=	2.00	
2	(	x	-	y	)	=	60.00	
2	x		-2	y	=	60	....................1	
60	/	(	x	+	y	)=	1.50	
1.50	(	x	+	y	)	=	60	
1.50	x	+	1.50	y	=	60	...............2	
Multiply (1) by 	3.00							
Multiply (2) by	4.00							
we get								
6	x	+	-6	y	=	180		
6	x	+	6	y	=	240		
12	x	=	420					
/	12							
x 	=	35	mph					
								
plug value of x in (1)								
2	x		-2	y	=	60		
70			-2	y	=	60		
-2	y	=	60	-70				
-2	y	=	-10					
	y	=	5	mph				
	Whale	35	mph					
	current    	5	mph					
								
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