小学四年级数学智力题， 求助。

我猜出答案的。请问怎么做和解释呢

A group of workers at Mr. Ramsey’s Ranch worked at the same pace. They were asked to mow two fields. One of the fields was twice as big as the other. They all mowed the larger field for half of a day. Then the group split in half. One group finished the larger field at the end of the day. The others mowed the smaller field. At the end of the day, there still remained a part to do. This part was finished by one worker in a single day. How many workers were there?