3. Joseph is a student in Prof. Yoon's business law class. Joseph is a smart student who has done well on his exams, but he knows that he is likely to get bad grade because of his excessive absences and his disrespectful behavior in class. Prof. Yoon always stresses the importance of the attendance and respectful behavior in class and warns students that these factors will influence the final grade a lot. One day near the end of the semester, Joseph hears from other students that Prof. Yoon is selling his business law textbook. A used business law textbook normally costs $10 to $80. Joseph offers to buy the book. from Prof. Yoon for $500. Prof. Yoon is so happy and accepts the offer. Prof. Yoon hands the book immediately to Joseph and Joseph gives $500 cash to Prof. Yoon. Furthermore, Prof. Yoon and Joseph write an agreement memorializing this transaction and sign the agreement. In that agreement, they explain how all four elements of contract are satisfied for this transaction. A few weeks later, Joseph receives a D+ as his final grade from Prof. Yoon. Joseph is very upset and goes to Prof. Yoon and demands all his money back claiming the book was overpriced. If Joseph takes Prof. Yoon to court, how will the court rule? In your response, you must use and apply all the relevant legal principles that you learned in class.

4. Al hires Carl, a contractor, for the renovation of Al's bathroom at the cost of $5,000. Afl.er Carl removes Al's bathtub and toilet, Carl walks away and refuses to continue without providing any explanation. Al promises to increase Carl's fee by an additional $2,000 and they draft a new contract to memorialize this increased fee. After that, Carl returns to work and finishes the job. Does Al have to pay Carl? Why or why not? Discuss the legal principles. (If you do not state the legal principle, you will not receive credit.)

5. Betty was 17 years old when she contracted to purchase a car from David's Car Dealer. She told the salesman that she was 21 years old and even showed him a fake driver's license. Since Betty did not have enough money so she financed most of the purchase price from David's Car Dealer. Six months later, Betty decided that she disliked her car and went to return the car to David's Car Dealer. Is David's Car Dealer required to take the car back? Is Betty responsible to pay for the rest of the balance, which she financed? You must state legal rules when you answer. Also, what if she did not lie about her age? Then, what is her liability?