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

The equation is $\"\"$

Subtraction property of equality: if $\"\"$ , then $\"\"$ .

$\"\"$ (Subtract 6.4 on both sides)

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

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

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

$\"\"$ (Divide both sides by 42)

$\"\"$ (Cancel common terms)

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

$\"\"$

The value of $\"\"$ .