若代數式12-3(9-y)與代數式5(y-4)的值相等,則y= ___.

若代數式12-3(9-y)與代數式5(y-4)的值相等,則y= ___.

根據題意得:12-3(9-y)=5(y-4),去括弧得:12-27+3y=5y-20,解得:y=52.故答案為:52.