$\"\"$

The equation is $\"\"$ .

According to addition property of equality: If a = b then a + c = b + c.

$\"\"$ (Add 13 to each side.)

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

$\"\"$

Check:

To verify the solution, substitute $\"\"$ in original equation.

$\"\"$ (Substitute 12 for z in the original equation.)

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

$\"\"$

The value of $\"\"$ .