Fifty part-time students were asked how many courses they were taking this term. The (incomplete) results are shown below. Need answers for part B and C

Answer:
The answer for B is 10% and for C is 40%.
Explanation:
To get the percentage for B you take the the frequecy of students taking 2 courses (5) and multiply it by 100 then you divide it by whole number of students.
For C you do the after adding the number of students taking 1 or 2 courses (20).