Question 23690
Look at my Lessons on Simultaneous equation, on this website... they help.


solution is:
x+3y=4 --eqn1
2x-y=8 --eqn2


scale up eqn1 by factor 2, giving:
2x+6y=8 --eqn1
2x-y=8 --eqn2


Now, the x-terms are the same digit...both a 2. Looking at the signs of these, they are the SSSSSSSSSame (both +), so we SSSSSSSSubtract the equations, to give:


5y = 0
so y = 0.


Hence, x+3y=4 becomes 
x+3(0) = 4
x = 4


and CHECK in the other equation:
2x-y=8 becomes
2(4)-0 = 8 
8=8 --> which is correct


jon.