Respuesta :

7c + 12 = -4c + 78 +4c. +4c 11c + 12 = 78 -12. -12 11c = 66 11/11. 66/11 C = 6 Plug in the answer to check . 7 * 6 + 12 = 54 -4 * 6 + 78 = 54 54 = 54