$\"\"$

The equation is $\"\"$ .

According to subtraction property of equality: If a = b then a $\"\"$ c = b $\"\"$ c

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

$\"\"$ (Apply commutative property: a $\"\"$ b = b $\"\"$ a)

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

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

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

The value of $\"\"$ .