### Theory:

If a number has no sign, then it is a positive number.
Example:
$$10$$ means $$+10$$.

$$56$$ means $$+56$$.
The sum of two positive numbers is always a positive number.
1. Add $$5$$ and $$10$$.

Step 1: $$5$$ and $$10$$ both are positive numbers. That is like signs. So, add those numbers.

Step 2: Here, both numbers are like signs. So, the answer is also the same sign.

$$5 + 10 = 15$$.

The sum of two negative numbers is always a negative number.
2. Add $$(-25)$$ and $$(-3)$$.

Step 1: $$(-25)$$ and $$(-3)$$ both are negative numbers. That is like signs. So, add those numbers.

Step 2: Here, both numbers are like signs. So, the answer is also the same sign.

$$(-25) + (-3) = -28$$.

The sum of positive and negative numbers keeps the sign of a larger number.
3. Add $$-56$$ and $$23$$.

Step 1: $$-56$$ is a negative number and $$23$$ is a positive number. That is unlike signs. So subtract those numbers.

Step 2: Here, $$56$$ is larger than $$23$$. The sign of $$56$$ is ($$-$$)negative.

$$(-56) + 23 = -33$$.