### Theory:

Subtraction means to add its opposite.
We can subtract two integers using a number line.
Example:
Solve $$6 - (-4)$$ using a number line.

Step 1: Change subtraction into addition, also change the sign of subtrahend.

$$6 - (-4) = 6 + (4)$$.

Step 2: Draw a number line with positive and negative numbers.

Step 3: Move $$6$$ units to the right of $$0$$.

Step 4: Now, move $$4$$ units to the right of $$6$$.

Step 5: The number reached is $$6 - (-4) = 6 + (4) = 10$$.