Scenario 3-2 Lincoln offers to do Katelyn's housework for $80 per week. Katelyn's opportunity cost of doing housework is $100 per week, and Lincoln's opportunity cost of doing housework is $50 per week. 39. Refer to Scenario 8-2. What is the total gain in welfare due to the transaction described above? a. $10 per week b. $20 per week c. $30 per week d. $40 per week