7
5.
A group of students calculated their average collection for charity.
They discovered that if one of them collected [tex]$200 more, their average collection would be $[/tex]240. If one of them collected [tex]$340 less, their average collection would be $[/tex]180.
How many students were there in the group?
(1)
13
(2)
9
(3)
5
(4)
4
( )
​