Choose between two gambles: draw a decision tree and solve the problem

You need to choose between two gambles. In the first gamble you have a 30% chance of receiving $100, a 50% chance of receiving $75, and a 20% chance of receiving $20. In the second gamble, you have a 40% chance of receiving $80, a 40% chance of receiving $60, and a 20% chance of receiving $50. Draw a decision tree to represent the problem. Solve the problem by rolling back the decision tree.