Question

4x+8y=20 -4x+2y=-30

Answer 1

4x + 8y = 20

-4x + 2y = -30

Adding the equations,

4x + 8y + (-4x + 2y) = 20 + (-30)

4x + 8y - 4x + 2y = 20 - 30

10y = -10

y =
`(-10)/(10)`

y = -1

Substituting the value of y in the first equation,

4x + 8y = 20

4x + (8 * -1) = 20

4x - 8 = 20

4x = 20 + 8

4x = 28

x =
`(28)/(4)`

x = 7

Hence, x is 7 and y is -1.

Answer 2

Hello,

4x+8y=20
-4x+2y=-30

What you can do here is add both equations together, so that 4x (from the 1st equation) and -4x (from the second equation) cancel out.

After doing that, you get
10y = -10
Therefore, y = -1.
Now, use y = -1 in the original equations.
4x + 8y = 20
4x + 8(-1) = 20
4x-8 = 20
4x = 28
x = 7

You also want to confirm your answers by plugging them in the other equation just to make sure.

-4x + 2y = -30
-4(7) + 2(-1) = -28 - 2 = -30

So, x = 7, and y = -1.
Hope this helped! :)