### Theory:

We can add two integers using a number line.

1. Add $$4$$ and $$3$$ using a number line.

Step 1: Draw a number line with positive and negative numbers.

Step 2: Move $$4$$ units from the right of $$0$$.

Step 3: Now, move $$3$$ units from the right of $$4$$.

Step 4: The number reached is $$4 + 3 = 7$$.

2. Add $$(-5)$$ and $$4$$ using a number line.

Step 1: Draw a number line with positive and negative numbers.

Step 2: Move $$5$$ units from the left of $$0$$.

Step 3: Now, move $$4$$ units from the right of $$-5$$.

Step 4: The number reached is $$(-5) + 4 = -1$$.

3. Add $$(-5)$$ and $$(-5)$$ using a number line.

Step 1: Draw a number line with positive and negative numbers.

Step 2: Move $$(-5)$$ units from the left of $$0$$.

Step 3: Now, move $$(-5)$$ units from the left of $$(-5)$$.

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