1. **State the problem:** We need to find the percent increase when the deductible mileage cost increased from 59.9 cents to 66.9 cents in 2011. 2. **Formula for percent increase:** $$\text{Percent Increase} = \left(\frac{\text{New Value} - \text{Old Value}}{\text{Old Value}}\right) \times 100\%$$ 3. **Substitute the values:** $$\text{Percent Increase} = \left(\frac{66.9 - 59.9}{59.9}\right) \times 100\%$$ 4. **Calculate the difference:** $$66.9 - 59.9 = 7.0$$ 5. **Calculate the fraction:** $$\frac{7.0}{59.9}$$ 6. **Show cancellation step:** $$\frac{\cancel{7.0}}{59.9}$$ (7.0 is numerator, no common factor to cancel with denominator, so fraction remains as is) 7. **Divide:** $$\frac{7.0}{59.9} \approx 0.1169$$ 8. **Convert to percent:** $$0.1169 \times 100\% = 11.69\%$$ 9. **Round to nearest tenth:** $$11.7\%$$ **Final answer:** The percent increase is **11.7%**.