What should be the minimum no of students in a class room given the following conditions? 
What should be the minimum no of students in a class room in which 25% student score 75 marks,10% student score 85 marks,15 % student score less than 50 marks, 25% score 60 marks and remaining student score more than 90 marks..

My Approach:
75 MARKS------------------------------->25%
80 MARKS------------------------------->10%
50 MARKS(LESS THAN)-------------->15%
60 MARKS------------------------------->25%
90 MARKS(REMAINING)------------>25%

How to solve this problem after this as I am unable to do after it?
2)What would be the answer if it would be atleast and almost number of students?


If you take the greatest common divisor of your percentages (which is easy to see is 5), then the minimum number of students is $100 / 5 = 20$ (Why?)
