Question 461151
boat 	speed=	x	mph					
current 	speed=	y	mph					
with stream speed=		(x+y) mph						
against stream speed =		(x-y) mph						
d=	20							
20/	(x+y) 	=	1.5				
divide by 	1.5							
13.33	/	(x+y) 	=	1				
(x+y) 	=	13.33	............1					
d=	20						
60/(x-y) 	=	3						
divide by 	3							
6.67	/(x-y)	=	3					
	x	-		y	=	6.67	.............2	
add up (1) & (2)								
2	x	=	20					
/	2							
x=	10	mph	speed of	boat 	in still water			
plug value of x in (1)								
we get 	y= 	3.33	mph	speed of	current