I have a rather strange formula I'd like to do. What I want is for a cell, lets say D1, to get a value that is a sum of all valid numbers in the range B1 to B100, where the only condition to be a valid number is that for each cell looked at (ie B1, B2, B3) it looks to the left at A1, A2, A3, and sees if it contains "true" or "false". If it's true, then it adds that to the sum, if not, it skips over it.

I thought there was a way you could do this with like vlookup or whatnot. I know I can do it with a macro, no problem, but I'm not 100% certain if there's a way to do this with a formula instead (which would automatically update the value in D1 if I change something in column A or B. That automatic update is the big thing I need.)