$\"\"$

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

The equation is $\"\"$

Apply subtraction property of equality: Subtract 6.4 from each side.

$\"\"$

$\"\"$ (Apply Additive inverse proparty: $\"\"$ )

$\"\"$ (Apply Additive identity proparty: $\"\"$ )

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

Apply division property of equality: Divide each side by 42.

$\"\"$

$\"\"$ (Cancel common terms)

$\"\"$ (Calculate the value using a calculator) $\"\"$

The value of $\"\"$ .