1. **State the problem:** You deposit 600 in a bank account with a simple interest rate of 2.5%. You want to find the time $t$ (in years) needed to earn at least 120 in interest. 2. **Formula for simple interest:** $$I = P \times r \times t$$ where $I$ is interest, $P$ is principal, $r$ is rate (as a decimal), and $t$ is time in years. 3. **Plug in known values:** $$120 = 600 \times 0.025 \times t$$ 4. **Solve for $t$:** $$120 = 15 \times t$$ 5. **Divide both sides by 15:** $$\frac{120}{\cancel{15}} = \cancel{15} \times t / \cancel{15}$$ $$8 = t$$ 6. **Interpretation:** You need to keep your deposit in the bank for at least 8 years to earn 120 in interest.