Question 419568
Merle took half an hour to row 3km with the current. When he returned, he took 90 minutes. Find his rowing rate and the speed of the current.

upstream time =		1.5	hours					
downstream time=		0.5	hours					
								
Distance = same								
boat speed	=x							
current speed 	=y							
t=d/r								
3	/	(	x	-	y	)=	1.50	
1.5	(	x	-	y	)	=	3.00	
1.5x-1.5	y	=	3	....................1	
3	/	(	x	+	y	)=	0.5	
0.5	(	x	+	y	)	=	3	
0.5	x	+	0.5	y	=	3	...............2	
Multiply (1) by 	1							
Multiply (2) by	3							
we get								
1.5	x	+	-1.5	y	=	3		
1.5	x	+	1.5	y	=	9		
3	x	=	12					
/	3							
x 	=	4	mph	boat speed				
								
plug value of x in (1)								
1.5	x		-1.5	y	=	3		
6			-1.5	y	=	3		
-1.5	y	=	3	-6				
-1.5	y	=	-3					
	y	=	2	mph	current speed