$\"\"$

The word “sum” indicates addition and the symbol is (+).

The word “equals” indicates the symbol (=) \ \

$\"\"$

The equation is $\"\"$

$\"\"$

According to subtraction property of equality; if $\"\"$ , then $\"\"$ .

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

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

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

$\"\"$

$\"\"$ (Multiply 6from each side)

$\"\"$ (Cancel common terms)

$\"\"$ (Multiply: $\"\"$ ) \ \

$\"\"$

The value of $\"\"$ .