4. x = 1/2 and y = 3
5. x = −5/7 and y = 16/7
6. No solutions.
7. x = 7 and y = 4
8. ( You already got that one but just in case ) No solutions.
9. x = 3/2 and y = 3
10. x = 1/5 and y = 0
11. x = 3 and y = −8/5
12. x = −48 and y = −45
13. x = 92/15 and y = 29/15
14. x = −38/3 and y = 21