Reason:
-4 - (-10) = -4 + 10 = 6
The two negatives cancel to form a positive.
Here's how to visualize what's going on: Draw a number line. Plot a marker at -4. Then move 10 units to the right and you should arrive at 6. This visually indicates -4+10 = 6
Another way to visualize: Imagine you are on basement level 4 of a tall building. If you move up 10 floors, then you'll arrive at the 6th floor. We treat the ground floor as floor 0. It might help to draw a vertical number line.
