The average runs scored by a batsman in 20 matches is 45. In the next 10 matches, the batsman scored an average of 14 runs. Find his average runs (rounded off to two decimals) in all the 30 matches.

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).