Question 806074
boat   	speed	=	15	mph														
current     	speed	=	x	mph														
																		
against 	current	=	15	-	x													
with 	current	=	15	+	x 													
																		
Total distance =		20	miles 		Total Time=	3.00	hours  											
Time upstream + time downstream =						3	hours  											
																		
20	/(	15	-	x 	)+	20	/(	15	+	x 	)=	3						
20	(	15	+	x 	)+	20	(	15	-	x 	)=	3.00	(	225	-	1	X^2	)
300	+	20	x	+	300	-20	x  	=	675	-	3	X^2						
600	-	-675	=			-3	X^2											
-75	=		-3	X^2														
-3	X^2=	-75																
X^2	=	25																
X =	+/-	5																
ignore negative
current speed = 5 mph