The average of 10 numbers is 45. When one specific number is removed from the set, the average of the remaining numbers becomes 42. What was the value of the number that was removed?

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).