Gas to oil ratio

Ok, got a question for all you people in the lawn service industry, dealers, or mechanics. I have Poulan weed eater and chainsaw that both say to use 40-1 mix and I just got a new Echo 250 power blower and it says to use 50-1 mix on the gas and oil.

I don't really want to have two gas cans sitting around ... what would be the better mix for all of them so that I could just use one can?

Thanks for taking the time to help me out here. Timm