1. **State the problem:** Simplify the expression $8 - 3(5 - 3^2)$. 2. **Recall the order of operations:** Parentheses, exponents, multiplication/division, addition/subtraction (PEMDAS). 3. **Calculate the exponent inside the parentheses:** $3^2 = 9$. 4. **Substitute back:** $8 - 3(5 - 9)$. 5. **Simplify inside the parentheses:** $5 - 9 = -4$. 6. **Expression becomes:** $8 - 3(-4)$. 7. **Multiply:** $3 imes -4 = -12$. 8. **Expression is now:** $8 - (-12)$. 9. **Subtracting a negative is adding:** $8 + 12 = 20$. **Final answer:** $20$