Question 427563

 speed in still water =	r		
current speed 	=3		
				
upstream speed = r-3		
downstream speed = r+3		
				
Distance= 12	miles		
				
Time upstream + time downstream = 5.33	hours

12/(r+3)	+12/(r-3	)=5.33
LCD =	(r-3)(r+	3)				
12*(r-3)	+12(r+3	)=	5.33
12r-36r+12r+36=5.33
r^2-24r=5.33r^2-47.97							
5.33r^2-	24r-47.97							
Find the roots of the equation by quadratic formula
a=5.33	b=-24	c=-47.97	
b^2-4ac=	576+1022.72										
b^2-4ac=	1598.72												
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}													
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}													
x1=(24+	39.98)/	10.66								
x1=	6												
x2=(24-39.98) /10.66									
x2= -1.5		( ignore)										
Speed = 6 mph