The average mark of the students of a class in a particular exam is 60. If 5 students whose average mark in that exam is 44 are excluded, the average mark of the remaining will be 80. Find the number of students who wrote the exam?  Pick one
A) 12
B) 10
C) 7
D) 9
E) 8

Rationale: "let the number of students who wrote the exam be x . total marks of students = 60 x . total marks of ( x - 5 ) students = 90 ( x - 5 ) 60 x - ( 5 * 44 ) = 80 ( x - 5 ) 180 = 20 x = > x = 9 answer : d"
Answer: D