2x - 4y = 20 4x + 2y = -20 - Computers & Internet

This should start wit X=something and Y=something, sorry I'm not an human algebra calculator....

You need to single out one of the variables but the same in both equations

for example 2x - 4y = 20 (mult by -1)
becomes -2x = -4y - 20

and in the other equation 4x + 2y = -20
becomes 4x = -2y - 20 (subtr 2y from each side)
becomes -2x = y + 10 (div by -2)

since -2x is singled out on both sides you take both formulas without the x and solve for y

so this: -4y - 20 = y + 10
becomes -5y = 30 (subtract 1y from each side and add 20 to each side)
becomes y = -6 (div by -5)

now you know what y is, plug it back into one of the original equations to find x

x = -2
y = -6


note* you could find what x is first by doing the same thing except singling out the y's instead of x's