$\"\"$

Elimination method:

The system of equations are $\"\"$ .

$\"\"$ ----------(1)

$\"\"$ ----------(2)

To get two equations that contain opposite terms multiply the first equation by negative 1. $\"\"$

Add the equations to eliminate the z - variable and solve the equation.

$\"\"$

The resultant equation is $\"\"$ . $\"\"$

The value of $\"\"$ substitute in either equation to find z.

First equation: $\"\"$ .

$\"\"$

Subtract 18 from each side.

$\"\"$

Divide each side by negative 4.

$\"\"$

The solution is $\"\"$ .