Pls Anyone Help. Premium Amount Calculation Problem

Need to calculate premium amount using two values. One such value is Age and another is Term length. You check a “multiplier” value when you check Age against Term Length and use it to calculate the premium rate. Example:

My Age is 20, Term Lenth desired is 10 years. Multiplier to use is 22.30. With my Face amount being 300,000. The premium amount will be:

(300,000*22.30/1000)+(50) = 6740

Note* 50 is Tax added to total. Multipliers are available. You check them against Age & Term Length.

My multiplier depends on the two factors. How can I make this work using Caldera Forms? Problem is how to create form to understand that if Age is 20 and Term length is 10 select multiplier 22.30 for use in calculating premium.