this is the GUI i creating for a calculating the state, county, total sales tax and total purchase price. im lost on how to code the sales and county tax buttons to combine eith the state and county text box strings

Form1.cs Form1.cs (Design)" X Sales Tax and Total Server Explorer Toolbox Data Sources Enter Purchase Price: Enter State: Enter County: State Sales Tax County Sales Tax Total Sales Tax Total Purchase Price Exit Error List Entire Solution 0 Errors A Warnings of 2 Messages Search Build - IntellSense Project Code File Line Description Dead