$\"\"$

The equation is $\"\"$ .

Apply addition property of equality: Add 7 to each side. \ \

$\"\"$

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

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

$\"\"$ (Add: $\"\"$ ) $\"\"$

Check:

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

$\"\"$ (Substitute $\"\"$ )

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

The solution is true. $\"\"$

The value of c is 18.