Question 934453
boat   	speed	=	11	km/h														
current     	speed	=	x	km/h														
																		
against 	current	=	11	-	x													
with 	current	=	11	+	x 													
																		
Total distance =		12	km 		Total Time=	2.75	hours  											
Time upstream + time downstream =						2.75	hours  											
																		
12	/(	11	-	x 	)+	12	/(	11	+	x 	)=	2.75						
12	(	11	+	x 	)+	12	(	11	-	x 	)=	2.75	(	121	-	1	X^2	)
132	+	12	x	+	132	-12	x  	=	332.75	-	2.75	X^2						
264	-	-332.75	=			-2.75	X^2											
-68.75	=		-2.75	X^2														
-2.75	X^2=	-68.75																
x2=	=	25																
x=   	+/-	5																
speed of current = 5 km/h