Question 427553
boat speed	=15	mph									
current speed 	=x	mph					
Speed upstream=	15-x									
Speed downstream=15+x						
Distance upstream=		10	miles										
Distance downstream=		20	miles			
t=d/r	time upstream = time downstream												
10/(15-x	)=20/(15	+x)
10(15+x)=20(15-x)			
150+10x=300-20x 					
20x-10x=150								
10	x	=	150										
/	10												
x =15mph	current speed