Answer:
30
Explanation:
6/0.20 = 30.
Since to Normally find a percentage of a number, you would Multiply the percentage in decimal form, multiplied times the full amount, to get a percentage. ( 30*0.2 = 6)
So to find the full amount (in this case of students) Reverse this process, and divide the Portion by the percentage (In this scenario, 6/0.20) and you will get the full amount.
I hope this helps!