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

The equation is $\"\"$

Subtraction property of equality: If a = b then a – c = b – c.

$\"\"$ (Subtract 20 from each side)

$\"\"$ (Commutative property: a + c = b + c)

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

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

$\"\"$ (Divide each side by 3) $\"\"$

$\"\"$ (Cancel common terms)

$\"\"$ (Divide: $\"\"$ )

$\"\"$ (Multiply each side by negative one)

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

The value of $\"\"$ .