Question 815142
Find boat speed & current speed			Both times given					
								
boat   	speed	=x	mph					
current     	speed	=y	mph					
against  	current     	3	hours					
with	current     	3.5	hours					
								
Distance against 		12	miles	distance with 		35	miles	
t=d/r	against	current     		-				
12.00	/	(	x	-	y	)=	3.00	
3.00	(	x	-	y	)	=	3.50	
3.00	x	-	3.00	y	=	12.00	....................1	
								
35.00	/	(	x	+	y	)=	3.50	
3.50	(	x	+	y	)	=	35.00	
3.50	x	+	3.50	y	=	35.00	...............2	
Multiply (1) by	3.50							
Multiply (2) by	3.00							
we get								
10.50	x	+	-10.50	y	=	42.00		
10.50	x	+	10.50	y	=	105.00		
21.00	x	=	147.00					
/	21.00							
x	=	7.00	mph					
								
plug value of x in (1)				y				
3.00	x		-3.00	y	=	12.00		
21.00			-3.00	-21.00	=	12.00		
-3.00	y	=	12.00					
-3.00	y	=	-9.00	mph				
	y	=	3.00					
boat   	speed	7.00	mph					
current     	speed	3.00	mph