От деревни до города велосипедист ехал 4 ч со скоростью 12 км  в час со скоростью 12 км в час. Сколько времени он потратит обратный путь по той же дороге, если увеличит скорость на 4км в час?

When I (to come in) she (to play) the piano.and she to (to say) she (to play) for 2 hours already.we (to go) to the institute when we (to meet) him yesterday.mother (to answer) she (to do) the flat for an hour but she (to be afraid) she would't be able to have finished it by their arrival.what you (to do) when I (to ring up) you yesterday?-I (to do) my lessons for next day.I (to see) she (to write) something and (to decide) hot to disturb her.