Weight attribution in regression model

Question

I am new to data science and I have a question regarding weight attribution in regression model. I have a dependent variable y which is the cost and independent variables a, b, c, d and e. e is a categorical variable which is a location. a, b, c and d are numerical variables. I want to attribute the cost to 'a' for different locations e. Which model can I use to attribute the cost? Or which model can explain how much of the cost is caused by 'a' for different locations e?

Really appreciate the help.