Question 535570

250/x + 120/y =4

substitue 1/x with a & 1/y with b
250a+120b=4

130/x + 140/y = 4.3

130a+140b=4.3

250    	a	+	120	b	=	4	.............1	
130	a	+	140	b	=	4.3	.............2	
Eliminate y								
multiply (1)by 		-7						
Multiply (2) by		6						
-1750	a		-840	b	=	-28		
780	a	+	840	b	=	25.8		
Add the two equations								
-970	a				=	-2.2		
/	-970							
a	=	0.00227						
plug value of 			a	in (1)				
250    	a	+	120	b	=	4		
0.57		+	120	b	=	4		
			120	b	=	4		-0.57
			120	b	=	3.43		
				b	=	0.02861		
x=1/a= 1/0.00227= 440 km/h-------------Train
y=1/b=1/0.02861= 35 km/h-------------- Car

CHECK
130/440 +140/35= 4.3 hours

m.ananth@hotmail.ca