1. **State the problem:** A phone plan costs 40 flat plus 0.20 per minute over 500 minutes. Last month the bill was 52. We need to find how many extra minutes were used. 2. **Set up the equation:** Let $x$ be the number of extra minutes used over 500. The total cost is given by: $$\text{Total cost} = 40 + 0.20x$$ 3. **Use the given total bill:** $$40 + 0.20x = 52$$ 4. **Solve for $x$:** Subtract 40 from both sides: $$0.20x = 52 - 40$$ $$0.20x = 12$$ Divide both sides by 0.20: $$x = \frac{12}{0.20}$$ $$x = 60$$ 5. **Interpretation:** The number of extra minutes used over 500 is 60. **Answer:** 60 extra minutes were used, which corresponds to option b.