In Ms. Berkeley's classroom 2/5 of the students play chess of the students to play chess 5/6 also play sudoku. if there are 30 students in Ms Barclays class how many play chess and sudoku?

10 students play chess and sudoku,

30*2/5 is 12, out of 12; the number of students that play chess, 5/6 play sudoku.

So ... 12*5/6 is 10 and that is the number of students that play both sudoku and chess.