$\"\"$

The equation is $\"\"$ .

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

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

(Apply commutative property of addition: a + b = b + a)

$\"\"$

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

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

Apply division property of equality: If a = b, then $\"\"$ .

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

$\"\"$ (Cancel common terms)

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

The value of $\"\"$ .