Question 548934
swimming rate = s
running rate =r
d=r*t
convert minutes to hours

First day
(3/4)s+(1/3)r = 9
LCD = 12
multiply equation by 12
9s+4r=108...............(1)

Day II
(1/2)s+(2/3)r= 9
LCD = 6
multiply equation by 6
3s+4r=54....................(2)

9	s	+	4	r	=	108	.............1		
3	s	+	4	r	=	54	.............2		
Eliminate 	r								
multiply (1)by 		-1							
Multiply (2) by		1							
-9	s		-4	r	=	-108			
3	s	+	4	r	=	54			
Add the two equations									
-6	s				=	-54.00			
/	-6								
s	=	9      							
plug value of 			s	in (1)					
9	s	+	4	r	=	108			
81		+	4	r	=	108			
			4	r	=	108		-81	
			4	r	=	27			
				r	=	6  3/ 4			
swimming rate	9    km/h							
running rate	6 3/4	km/h
						
m.ananth@hotmail.ca