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=5409с=540+1809с=720/9с=80