F.1未知數(數學)

There were 39 students in the classroom of S1A and 42 students in the classroom of S1B. Then, some students form the classroom of S1A entered into the classroom of S1B , and 2 students left the classroom od S1B . Finally, the number of students in the classroom of S1B was 3 more than that of S1A. How many students form the classroom of S1A entered into the classroom of S1B?(可能有D字會打錯,SOR。)

Let X be the number of students form the classroom of S1A entered into the classroom of S1B.


∴There were students in the classroom of S1A and students in the classroom of S1B finally.


∴




(有 係要寫的answer)(要長細列式)(THX了!)