1. **State the problem:** Simplify the expression $30 - 3(2^3)$. 2. **Recall the order of operations (PEMDAS):** Parentheses, Exponents, Multiplication and Division (left to right), Addition and Subtraction (left to right). 3. **Calculate the exponent:** $2^3 = 8$. 4. **Substitute back:** The expression becomes $30 - 3 \times 8$. 5. **Perform multiplication:** $3 \times 8 = 24$. 6. **Perform subtraction:** $30 - 24 = 6$. 7. **Final answer:** $6$.