$\"\"$ $\"\"$

The equation is $\"\"$

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

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

$\"\"$ (Commutative property: $\"\"$ )

$\"\"$ (Additive inverse property: $\"\"$ )

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

Check:

To check the solution, substitute $\"\"$ in original equation.

$\"\"$

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

Compare the values, the equation is true.

$\"\"$

The value of $\"\"$ .