Move all terms not containing c to the right side of the equation.
Subtract 12 from both sides of the equation.
Subtract 12 from 19.
Multiply each term in -c=7 by -1
Multiply each term in -c=7 by -1.
Multiply -1 by -1.
Multiply c by 1.
Multiply 7 by -1.
Solve for c 12-c=19