x=2, y=1. x=1, y=2. x=6, y=1. x=3, y=21. x=7, y=7. x=23, y=−1. x=2, y=1. x=35, y=20. x=2, y=1. x=1, y=2. x=3, y=2. x=1, y=2. x=4, y=3. x=12, y=4. x=12, y=21. x=5, y=7. x=5, y=2. x=18, y=6. x=3, y=2. x=3, y=2. x=7, y=8. x=8, y=−2. x=a(a−b), y=b(a+b). [2]Exercise66. A, $520; B, $440. 23 and 17.