Question 426890
against current		3.67	hours					
with current		1.83	hours					
								
Distance = same=55						
boat speed	=x							
current speed 	=y							
t=d/r								
55/(x-y)=3.67	
3.67(x-y)=55.00	
3.67x-3.67y=	55	....................1	
55/(x+y)=1.83	
1.83(x+y)=55	
1.83x+1.83y=	55	...............2	
Multiply (1) by 1.83							
Multiply (2) by	3.67							
we get								
6.72x-6.72y=	100.83		
6.73x+6.73y=	201.85		
13.45	x=302.68					
/13.45							
x=22.5mph boat speed				
								
plug value of x in (1)								
3.67x-3.67y=	55		
82.51-3.67y=	55		
-3.67	y=	55	-82.51				
-3.67	y=	-27.51					
	y=	7.5	mph	current speed