Exercise 2.67 from the book
Exercise 2.68 from the book
Exercise 2.69 from the book
Exercise 2.70 from the book
Exercise 2.71 from the book
Exercise 2.72 from the book
Exercise 2.73 from the book
Exercise 2.74 from the book
Exercise 2.75 from the book
Exercise 2.76 from the book