1. **State the problem:** Gem Treasure earns 40000 a year and pays income tax at 15%. We need to find her net income after tax. 2. **Calculate the amount of tax paid:** The tax is 15% of 40000, so calculate: $$\text{Tax} = 0.15 \times 40000 = 6000$$ 3. **Calculate the net income after tax:** Subtract the tax from the total income: $$\text{Net Income} = 40000 - 6000 = 34000$$ 4. **Conclusion:** Gem Treasure's net income after tax is 34000. **Answer: c. 34000**