If you put high effort there is 30% chance of contributing $100 and 70% chance of $200,  The cost of high effort to you is $20. If you put low effort, there is 40% chance of contributing $20 and 60% chance of $100.  The cost of low effort is zero. If your contribution is $100 or higher, you will get a Bonus of B dollar. For what value of B, will you put high effort?   (Hint: you will put high effort if your expect income net of cost is higher from high effort than from low effort)