Needing Assistance with an Excel Formula

[littlemisspop14]

Hi there, can someone please help me with an excel formula? 

If column E rows 7 to 24 have the word plumbing (which come from a drop down box) I want it to subtract column D rows 7 to 24 from column G rows 7 to 24.

[#2]

@littlemisspop14 I have difficulties matching your questions to the screenshot so I created a file containing an example of what I think you are needing, using the SUMIF function. I trust you can adapt it to your own data.