$\"\"$

The equation is $\"\"$ .

$\"\"$ (Write the equation)

Apply subtraction property of equality: if $\"\"$ .

$\"\"$ (Subtract 18 from each side)

$\"\"$ (Rewrite as the summation)

$\"\"$ (Apply additive inverse property: $\"\"$ )

$\"\"$ (Apply additive identity property: $\"\"$ )

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

The solution is $\"\"$ .