$\"\"$

The expression is $\"\"$

$\"\"$ (Replace y with 3 and z with 9 in original expression)

$\"\"$

By the order of operations (PEMDAS):

Since there are no grouping symbols and powers,

First operation is multiplication.

$\"\"$ (Multiply: $\"\"$ )

$\"\"$

Next operation is subtraction.

$\"\"$ (Subtract: $\"\"$ )

$\"\"$

The value of the expression is 27.