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

The equation is $\"\"$ .

$\"\"$ (Product of two same signs is positive)

Apply subtraction property of equality: Subtract 18 from each side.

$\"\"$

Apply commutative property of addition: $\"\"$ .

$\"\"$

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

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

Verify:

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

$\"\"$

$\"\"$ (Product of two same signs is positive)

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

Compare the values, the equation is true. $\"\"$

The value of f is 73. \ \