1. **State the problem:** We need to find the percent change when the area increases from 100 acres to 140 acres. 2. **Formula for percent change:** $$\text{Percent Change} = \frac{\text{New Value} - \text{Original Value}}{\text{Original Value}} \times 100\%$$ 3. **Identify increase or decrease:** Since 140 acres is greater than 100 acres, this is an increase. 4. **Calculate the change:** $$\text{Change} = 140 - 100 = 40$$ 5. **Calculate the percent increase:** $$\text{Percent Increase} = \frac{40}{100} \times 100\% = 40\%$$ 6. **Interpretation:** The area increased by 40 percent. **Final answer:** The percent increase is **40%**.