Question

8x-4y=20

Answer 1

what are you solving for?

Answer 2

x=15/6
solve for one variable and plug it back into the original equation to get the other..
so 8x-4y=20
4y=8x-20
y=(8x-20)/4----y=2x-5
plug y value back into original equation??
this may not be right!!!

Answer 3

8x-4y=20 first divide everything by 4 and you get:
8x/4-4y/4=20/4
2x-y=5 add y
2x-y+y=5+y
2x=5+y divide by 2 to isolate x
2x/2=(5+y)/2
x=(5+y)/2 so far you solved for x
Now if you want to solve for y here is what you do:
8x-4y=20 first divide everything by 4 and you get:
8x/4-4y/4=20/4
2x-y=5 subtract 2x
2x-2x-y=5-2x
-y=5-2x divide by (-1) both sides of the equation
(-1)(-y)=(-1)(5-2x)
y=-5+2x or y=2x-5
This is as far as you can go with these kind of equation, unless you are given more info.

Answer 4

dwelsher suggests to plug back into the original equation, but that would give you 0=0... and you did not find x nor y.