$\"\"$

Since the given polygon is 18-gon, $\"\"$ .

The sum of the measures of interior angles of a polygon is $\"\"$ .

$\"\"$ (Interior angle sum theorem)

$\"\"$ (Substitute $\"\"$ )

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

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

The sum of the measures of the interior angles is 2880.