Your answer is <span>{2, 8, 12}. The way you get this answer is by setting the function 2x - 4 equal to 0, 12, and 20 and solve for x. Your x-values become 2, 8, and 12</span>
X= 45, you would place 15 into y's place, which would give you x-15= 30... then you would add 15 to both sides, which would give you x=45<span />
-4, because it is four units away from zero.