What is the difference between = and ==

Give the output of the following expression:
a+= a++ + ++a + --a + a--; when a = 7;

What will be the output of the following code?

int k=5,j=9;
k+= k++ - ++j + k;
System.out.println("k="+k);
System.out.println("j="+j);

What is the value of y after the execution?
y+= ++y + y-- + --y; when int y=8