Question 874240
boat   	speed	x	mph	with no	wind   		
wind   	speed	4	mph				
							
against	wind   	x	-	4	mph		
with	wind   	x   	+	4	mph		
							
Distance against	wind   	20					
Distance with	wind   	60					
Time = same	equate the time against with time with current						
t=d/r							
20	/(x-	4	)=	60	/(x+	4	)
20	*(x+	4	)=	60	*(x-	4	)
20	x  	+	80	=	60	x	-240
20	x  	-60	x   	=	-240	+	-80
-40	x  	=	-320				
/	-40						
	x=	8	mph				
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