How can I limit the max int value of 2nd drop down box based on int value of first?

I have a small and what feels like it should be a simple issue but so far with various internet searching I simply can't figure out how to solve my problem.

I need whichever values in both dropdown boxes to equal 100 when summed together. The value of the first should limit what I can use in the second.

I've got a cell with a dropdown box which refers to a named range that has numbers from 0-100.

The ideal functionality would work like this:

If I chose 50 in the first dropdown box, the maximum value I can choose in the second is 50.

If I chose 10 in the first dropdown box, the maximum value I can choose in the second is 90.

If I choose 100 in the first one, the max value I can choose is 0 in the second dropdown box.

I 've seen various ways to make dependent dropdown boxes with text lists but I can't figure out how to make this work as described above based on a sum of both.

Thank you guys! I was not able to understand this reading it on the web but from the examples that work here I can see what is happening and I am sure I can get it to work in my spreadsheet thank you again. :D

Hi, I really like your drop example and 2 options here. However, I am struggling to understand how you created "name2" with the offset formula - I don't see this in the drop down name box. I am attempting to use what you provided, but I also want to add additional "Inputs" and those drop down quantities will continue to reference the prior selection and limit of 100. In other words, is there a dynamic way to add more inputs that also have a drop down that all adhere to the qty 100 rule? My example is actually 40 total, but I was hoping there's a way to duplicate the formula so I can add more inputs and still have it know 40 is my max amount until all is used.

Thanks