1. **State the problem:** Solve the equation $$18 = \frac{a}{3} - 12$$ for the variable $a$. 2. **Add 12 to both sides** to isolate the term with $a$: $$18 + 12 = \frac{a}{3} - 12 + 12$$ $$30 = \frac{a}{3}$$ 3. **Multiply both sides by 3** to solve for $a$: $$3 \times 30 = 3 \times \frac{a}{3}$$ $$90 = \cancel{3} \times \frac{a}{\cancel{3}}$$ $$90 = a$$ 4. **Final answer:** $$a = 90$$ This means the value of $a$ that satisfies the equation is 90.