There are three teams that collected a total of 65 books
Team 1 -x
Team 2- x+ 10
As team 2 collected 10 books more than team 1
Team 3 -30% of (x + x+ 10)
Team 3 collected 30% of the books that team 1 and team 2 collected in total
The equation for the total number of books is;
x + x + 10 + 0.3(2x+10) = 65
2x + 10 + 0.6x + 3 = 65
2.6x +13 = 65
2.6x = 52
x = 20
Team 1-20 books
Team 2 -30 books and
Team 3 - 15 books