How can one utilize Excel to solve the following problem?...

Start with the original data set...

Period 1 = 30
Period 2 = 60
Total = 90

For example, say you wanted to increase the number of periods to 3 while distributing the original data over those periods.

Period 1 = (2/3)*30 = 20
Period 2 = (1-2/3)*30 + (1-(1-2/3)*60 = 10 + 40 = 50
Period 3 = (1-2/3)*60 = 20
Total = 90

This is a very basic example. It gets much more complex when the number of periods vary, and the difference between the number of periods varies. How do utilize Excel to extrapolate the original X period data set over Y periods with a linear distribution?

Thank you for your help!