o mow a grass field a team of mowers planned to cover 15 hectares a day . after 4 working days they increased the daily productivity by 33 × 13 % 33 × 13 % , and finished the work 1 day earlier than it was planned . a ) what is the area of the grass field ? b ) how many days did it take to mow the whole field ? c ) how many days were scheduled initially for this job ?