Difficult (for me) question about conditional SUM

thanks, but I actually have to make it even harder.

Let's make this example. I have column A containing either true or false and column B containing either number or #N/A. I need a formula (if it does exist) that calculate the average of those values in column B that are valid (ie not #N/A) and whose corresponding test condition in the same row and column A is true. At this point I would accept even VBA code but i don't understand much about it so I would need some big help on that.

Sorry for abusing your patience.

Thanks again for your support.

Paolo

Italy