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 \(6\).
 
Numberline_7.png
 
Step 5: The number reached is \(6 - (-4) = 6 + (4) = 10\).