Решить уравнение C•9-180=540

С*9-180=540
9с=540+180
9с=720/9
<span>с=80</span>

С*9=540-180                                                                                                               с*9=360                                                                                                                    с=360:9                                                                                                                     с=40                                                                                                                         ответ:40(всё очень легко)))))))))))