Question

Given the equation 3x + y = - 4, how do you solve for y?

Answer 1

If `a=b` then `a-k = b-k`

That is we can subtract the same amount from both sides of an equation and the equation is still true.

Subtract `3x` from both sides of `3x+y=-4` and we will get
`y = -4 -3x`
or, if you like
`y = -(3x+4)`