1. **State the problem:** Simplify the expression $(2ba)^4$ using the power of a power rule. 2. **Recall the power of a power rule:** When raising a product to a power, raise each factor to that power: $$ (xy)^n = x^n y^n $$ 3. **Apply the rule:** $$ (2ba)^4 = 2^4 \cdot b^4 \cdot a^4 $$ 4. **Calculate powers:** $$ 2^4 = 16 $$ 5. **Write the simplified expression:** $$ 16 b^4 a^4 $$ 6. **Note:** The original answer given was $16 b^4$, but the correct full simplification includes $a^4$ as well. Final answer: $$16 b^4 a^4$$