ПОМОГИТЕ!!!
нужен доклад о фигурном катании 
для 8 класса
НА ЗАВТРА

як знайти 1/2 від 28 ????

1)    Как определить, какое окончание следует писать у имени прела -                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       гательного в безударном положении?-

Во сколько раз возрастет скорость реакции в гомогенной системе 2A + 3B = C, если концентрацию вещества A увеличить в 3 раза, а концентрацию вещества B в 2 раза?