Question

Solve the system by substitution.
-Y = x
-7x – 5y = –20

Answer 1

`x=10\\y=-10\\`

`(10,-10)`

Explanation:

`-y=x`

`-7x-5y=-20`

Substitute
`-y` for
`x` in the second equation:

`-7(-y)-5y=-20`

Multiply:

`7y-5y=-20`

Combine like terms:

`2y=-20`

Divide both sides of the equation by the coefficient of
`y`, which is
`2`:

`y=-10`

Now, substitute
`-10` for
`y` in the first equation:

`-(-10)=x`

Multiply:

`x=10`