How to get the overall complexity result base on Low, Medium and High

Hello Team,

Need help in creating a formula that will summarized or get the overall results base on 3 level category. "Low" "Medium" and "High"

Column A3:A14 are my process and column B3:B14 are its complexity. On column B15 I want to show the overall complexity of my business only answerable by only Low, Med and High.

I tried several formula but my returning values is not what Im expecting.

Appreciate all the help I can get.

Many thanks