Question 509037
Boat speed	=	4	mph										
current speed 	=	x	mph										
wind speed													
speed against	current	4	-	x									
speed with	current	4	+	x									
													
Distance against	current	2.5	m 										
Distance with 	current	5	m 										
													
t=d/r	time against = time with												
2.5/(4-x)=5/(4+x)
2.5(4+x)=5(4-x)			
10+2.5x	=20-5x 					
5x+2.5x	=10								
7.5x=10										
/	7.5												
x =1.33	mph	current speed