What is 4 plus -9 equals equals?

Answer 1

-5

Answer 2

4 + -9 = -5. If you start at zero, and move to the right(positive) 4 units on the number line. Then from there you are adding negative, so you are moving to the left 9 units. You will end up at -5 (5 units to the left of zero).

Think about it this way. You're in a car on a road that runs East West. Let East (right) be positive and West (left) be negative. Now let driving forward be adding, and driving in reverse be subtracting.

So your starting point is zero. So 4 + -9 means we add 4 to zero, then add -9:

• Point your car East (positive) and drive forward (add) 4 miles.
• Now turn your car towards West (negative) and drive forward 9 miles.
• You are now 5 miles West (negative) of your starting point. (-5)

Another one. Suppose you have 3 - -2:

• Point your car East (positive) and drive forward (add) 3 miles.
• Now turn your car towards West (negative) and drive in reverse (subtract) 2 miles.
• You are 5 miles East (positive) of your starting point. (+5 or just 5).

I chose East and West because it follows the same directions as the number line.