Question 475645
boat 	speed=	x	mph						
current 	speed=	y	mph						
with stream speed=		(x+y) 							
against stream speed =		(x-y) 							
d=	30								
30	/	(x+y) 	=	2					
divide by 	2								
15	/	(x+y) 	=	1					
(x+y) 	=	15	............1						
d=	=	27							
27/(x-y) 	=	3							
divide by 	3								
27	/(x-y)	=	3						
x-y	=	9	.............2		
add up (1) & (2)									
2	x	=	24						
/	2								
x=	12	mph	speed of	boat 	in still water				
plug value of x in (1)									
we get 	y= 	3	mph	speed of	current 				
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