Average Yearly Salary

Average Yearly Salary

Hi, we have a salary form, and in our country you get an extra salary in december (the average of your salary across the year)

Is there any way to make a formula, analytic or any way I could calculate the average salary across time?



Example:

last year my salary on the first 3 months was 100, but the other 9 months i was raised to 150

my yearly salary would be ((100*3)+(150*9)/12