Question 433951
Boat speed	=	12	mph										
current speed 	=	x	mph										
wind speed													
speed against  	current	12-x						
speed with 	current	12+x					
Distance against current 30 mph										
Distance with 	current	45	mph					
t=d/r	time upstream = time downstream												
30/(12-x)=45/(12+x)
30(12+x)=45(12-x)			
360+30x	=540-45	x 					
45x+30x	=180								
75x=180										
/75												
x=2.4	mph	current speed