How do you determine the answer to (-5) 4 and explain the steps using a number line?

To determine the answer to (-5) × 4, you can visualize it on a number line. Start at 0 and move left, since multiplying by a negative number indicates a direction to the left. For each of the 4 steps, move 5 units left: from 0 to -5, then from -5 to -10, from -10 to -15, and finally from -15 to -20. Thus, (-5) × 4 equals -20.