Checking off items on one sheet when selected on another

hey guys, new here.. i did some searching and cannot find what im trying to do. starting to think its not possible.
i have a sheet, with multiple pieces of equipment at work (excavators, loaders, dozers, etc). each type of machine has multiple drop dwn lists in a column. on sheet 2 (equipment), are the lists of all the gear. im looking for a formula on sheet 1 (projects) where for example, under LARGE EXCAVATOR, I pick "10-321 / LB 330 LS". once i pick it under the first drop down, i would like it to strikethrough on sheet 2. then i move on to the second drop down on the projects sheet under LARGE EXCAVATOR. now i pick "10-360 / CAT 336". now i would like that piece of gear to strike through on equipment sheet 2. basically thye end game is that when any given piece of gear on sheet one is picked from any drop down list, that it is checked off on sheet 2. this will just make things easier for me when i need to know if we have iron available or if its already on a specific job.

the only thing so far that has worked for me is selecting the list, under conditional formatting, new rule, format only cells that contain, selecting the cell value to equal to, selecting my 1st drop down list on sheet 1, formatting with strikethrough. this way works for me but would take forever to format every cell, and i cannot figure out how to copy that condition to every drop down list on sheet 1.

i attached the file im working with right now, ive been struggling with this for a couple days and hope to find some input.

thanks

Welcome to the forum.

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Welcome to the forum.

We would very much like to help you with your query, however the thread title does not really convey what your request is about. Tell us what you are trying to do, not how you think it should be done.

Please take a moment to amend your thread title. Make sure that the title properly explains your request. Your title should be explicit and not be generic (this includes function names used without an indication of what you are trying to achieve).

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Do you mean that you don't want it to appear in the drop-down once it's been chosen?

OK - can you please mock up in your workbook what you want where you want to see it.

So if a named equipment appears anywhere on "Projects", it should be crossed off on "Equipment"?
In your example, 10-321 / LB 330 LS is used twice. Should that be allowed?

Or are you asking that the formatting of the strikethrough actually appear in your dropdown? The formatting won't carry over to the data validation unfortunately. It would be easier (as suggested by Ali) that once used, the piece of equipment disappears from the dropdown list.

what you mean by "Used Twice"?

10-321 / LB 330 LS appears in Projects cell A3 and A155

Selecting Equipment!=$B$4:$K$14 > Conditional Formatting > New Rule > Use Formula

Formula:

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Yes, there are plenty of examples out there. Actually, for this one, it might have been easier to use
=COUNTIF(Projects!$A$1:$N$187,B4)>0