The average weight of 35 students in a class is 40 kgs. Five of the students of this class whose average weight is 42 kgs left the class. Find the average weight of the remaining 30 students.

The average of 100 numbers is 40. If one of the numbers, 30, is replaced by 70 while keeping the other numbers same, what is the new average?

The arithmetic mean of 22.5, 56, 42.5, 2x + 1, x - 2, 3x, and 36 is 30. Find the value of x (where x > 0).