Change of the average when a number is removed

Question

The average of 21 members is 30. The largest number is 50. If we remove the largest number then the average of remaining numbers will be?

Answer 1

The sum of the thirty numbers is $n \cdot \overline x= \color{blue}{21} \cdot \overline x$, where $\overline x$ is the average of the thirty numbers.

Edit: blue printed have been edited.

Then subtract the largest number from the result. After that, divide the new result by (n-1).