the average mark of the students of a class in a particular exam is 80 . if 8 students whose average mark in that exam is 20 are excluded , the average mark of the remaining will be 90 . find the number of students who wrote the exam .
n0 = 80.0
n1 = 8.0
n2 = 20.0
n3 = 90.0
t0 = n1 * n3
t1 = n1 * n2
t2 = n3 - n0
t3 = t0 - t1
answer = t3 / t2
print(answer)