Rate Definition based on Formula to fetch details from element entries.

I need to create a formula with conditions to choose

a)If basic salary <21000 then, return the amount 'Basic Salary'

b)If Basic Salary is between 21000 and 11000, then return '11000'

c)If not, return 0

Can we achieve this condition using the formula type 'HCM Rates Calculate Value'?

Any suggestions and samples to fetch the DBI for element entries to the formula type would be helpful.