. If you line up in three rows, there will be neither more nor less: if you line up in five rows, there will be two people missing, and if you line up in seven rows, there will be four people missing.
It can be understood that there are three more people than multiples of 3, 5 and 7.
The least common multiple of 3, 5 and 7 is 105.
Then the number of students is: 105+3= 108.