$\"\"$

\

The expression is $\"\"$ .

\

$\"\"$ (Replace y, z and x with 4, 2 and $\"\"$ )

\

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

\

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

\

$\"\"$ (Absolute value of $\"\"$ is 3)

\

$\"\"$ (Add: $\"\"$ ) $\"\"$

\

The value of the expression is 21.

\