1. **State the problem:** Calculate $25 + (-21) \div -4$. 2. **Recall order of operations:** Division comes before addition. 3. **Calculate the division first:** $$-21 \div -4 = \frac{-21}{-4} = \cancel{-}\cancel{21} \div \cancel{-}\cancel{4} = \frac{21}{4} = 5.25$$ 4. **Now add 25 to the result:** $$25 + 5.25 = 30.25$$ 5. **Final answer:** $30.25$