How to get 2 columns conditionally formatted against each other.

Hi, I hope some one can help, because I'm not sure you can do this.

I wish to compare two columns with payments, one from the bank and one from accounting.
Let me show you what I mean:


I've been doing this manually, and it's starting to annoy me that I'm not smart enough to automate this.

So, on one side -71515,84 is the same as the sum of the numbers on the right side. What I have to do is to check against the date, then do the sum and see if it's correct. I'd rather just mark it if it's correct and check the ones that are not.

Can I do this with conditional formatting?

Thank you!