Question 930777
Boat speed	=	15	mph										
current speed	=	x	mph										
													
speed against	current	15	-	x									
speed with	current	15	+	x									
													
Distance against	current	8	miles										
Distance with	current	12	miles										
													
t=d/r	time against = time with		current	-									
8	/	(	15	-	x	)=	12	/	(	15	+	x	)
8	(	15	+	x 	)=	12	(	15	-x	)			
120	+	8	x	=	180	-	-12	x					
12	x	8	x		180	+	-120						
20	x	=	60										
/	20												
x	=	3	mph	current	speed