Answer:
18 pieces
Explanation:
divide 30 by 5
you'll get 6
so one-fifth is equivalent to 6 of the pieces
multiply 6 by 2
you'll have 2 so two-fifths is equal to 12 pieces of rice crispy treats
subtract 12 from 30
30 - 12 = 18
So she took 18 pieces to school.