Решить уравнение C•9-180=540

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

с*9-180=540 9с=540+180 9с=720/9 с=80