Question

how to get 4(x-y)=12

Answer 1

divide both sides by 4
subtract 12 from both sides
add y to both sides

this will get a slope intercept form.

Answer 2

Distribute the 4 into the parenthesis and you'll get 4x-4y=12.

Then subtract the 4x and your problem becomes -4y=-4x+12

Divide by -4 to get the y alone, and the equation is now just y=x-3 which is set in slope-intercept form. (i think that's what you meant by solve)

Answer 3

x=-8 correct?