Question 570821
Boat speed	=	18	mph										
current speed 	=	x	mph										
wind speed													
speed against	current	18	-	x								0.07	
speed with	current	18	+	x									
													
Distance against	wind	10	km										
Distance with 	wind	14	km										
													
t=d/r	time against = time with												
10/(18-x)=	14/(18+x)
10(18+x	)=14(18	-x)			
180+10x	=252-14	x 					
14x+10	x	=	72								
24	x	=	72										
/	24												
x 	=	3	mph	current speed