C＃Dictionary应用程序：通过选择键来应用值

I have a dictionary that I am using to define the ratings of copper cable. I want to use these values to calculate how many cables it will take to meet a certain connections rating. The size of the connection, the cable type, and system type are selected by two ComboBoxs named cb_amperage, cb_cable_size and, cb_system_type. The answer found once the equation runs is to be displayed in a text box named tb6_cable_qty. I welcome any and all comments and suggestions. Thank you in advance for the assistance.I have a dictionary that I am using to define t