Consider the following fragment of a Java program:

int sum, a, salary, increase; sum = sum + a; salary = salary * increase;

It can be abbreviated as follows:

sum += a; salary *= increase;

In general, the assignment:

can be abbreviated as:x = xoperator expression

xoperator=expression

For each of the arithmetic operators `+`, `-`, `*`,
`/`, `%`, there is the corresponding combined assignment
operator `+=`, `-=`, `*=`, `/=`, `%=`.