X=12 because you would sub the 3 on both sides
Answer:

Step-by-step explanation:
A quadratic equation in one variable given by the general expression:

Where:

The roots of this equation can be found using the quadratic formula, which is given by:

So:

As you can see, in this case:

Using the quadratic formula:

Therefore, the answer is:

Answer:
on the number line make an open circle at 80 (am open circle is this: ○) and connect that to an arrow that points back to 0 and the negative numbers. It doesn't matter how far back as long as you make it an arrow