3. all of them except the third, seventh, and eight.
14. 2.4
15. 2
16. 2.4
17. 2.4
18. 6
19. 5
20. 4
21. 7
22. 0
28. System.out.println( (a+b)/2 );
30. a++;

31. a *= 3;
36. Error
37. There is a space between the minus sign and the equals sign.
42. The problem is that you divided two integer values in order to get a double or decimal value. You need to add a .0 to the end of one of the numbers.
43. The problem is that you put the plus sign after the equals sign. Change the code to a += 3;.
45. System.out.println( (1+7+9+34)/4 );
51. System.out.println( "a3+b3=c3" );