Answer:
Mr. Smiths class has 12 students and Mrs. Brown's class has 10 students.
Explanation:
if 1/3 of the class is absent and that amount is four you would multiply 4 by 3 and get 12. If 2/5 of the class are missing and there 4 students first you would divide 4 by 2 and get 2, then you would take the 2 and multiply it by 5 and get 10.