Question 933488
boat   	rate	=x	mph					
current     	rate	=y	mph					
against  	current     	15	hours					
with	current     	7.5	hours					
								
Distance against 		105	miles	distance with 		105	miles	
t=d/r	against	current     		-				
105.00	/	(	x	-	y	)=	15.00	
15.00	(	x	-	y	)	=	7.50	
15.00	x	-	15.00	y	=	105.00	....................1	
								
105.00	/	(	x	+	y	)=	7.50	
7.50	(	x	+	y	)	=	105.00	
7.50	x	+	7.50	y	=	105.00	...............2	
Multiply (1) by	7.50							
Multiply (2) by	15.00							
we get								
112.50	x	+	-112.50	y	=	787.50		
112.50	x	+	112.50	y	=	1575.00		
225.00	x	=	2362.50					
/	225.00							
x	=	10.50	mph					
								
plug value of x in (1)				y				
15.00	x		-15.00	y	=	105.00		
157.50			-15.00	-157.50	=	105.00		
-15.00	y	=	105.00					
-15.00	y	=	-52.50	mph				
	y	=	3.50					
boat   	speed	10.50	mph					
current     	speed	3.50	mph					
								
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