Need help with creating a dependant drop down menu that performs calculations

Alrighty so I'm pretty new at excel and it's proving to be quite the PITA to figure this stuff out. I've done a lot of searching but can't seem to find the answers that I need.

Sorry if this isn't in the right section, any help or even pointing me in the right direction would be greatly appreciated. I've done the best I can to explain what I'm trying to do and attached an example for reference to give you an idea.


So this is what I'm trying to do:

I'm creating a spread sheet that helps me write up estimates as a contractor.

On page 1 I have the main page with drop downs and information for the estimate, page 2 has the values (source data) for the drop down menus.

This is how I need it to work.

Drop down 1 would give me a list of different trades for the work

Drop down 2 would give me a list of associated tasks for each trade.

After making a selection in drop down 2, I want multiple cells to be populate with data based on the selection.

I need the first cell to be my variable data where I enter how much of an item to order,
the next cell to display the cost per unit, another cell to show the default unit of measurement assigned to each item(Per FT, IN, SQFT, etc.),
another cell to show the tax per item
(calculated by multiplying the taxable amount from the source sheet associated with the line item, times the entered value for the item, times the tax rate entered in a different cell at the top of the the estimate page)

I've attached a workbook to give you a visual idea of what I'm talking about

Please help!

Thanks for the reply!

I didn't include the actual work book because it doesn't exist yet lol. I need to get this part figured out before I can start it.

Your answer helped me for half of my question. I kind of already had an idea of how to do that part. What I need to know now is how to have the selections from the drop down calculate the equations I mentioned above and in my example work book