A library has an average of 510 visitors on Sundays and 240 on other days. Find the average number of visitors per day in a month of 30 days beginning with a Sunday.

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).