I should be able to figure this one out, but I can't. So any help is appreciated. What is the formula for figuring out what octane will result from blending gas of one octane with gas of a different octane? If they're blended 50/50, it's easy. But, any other blend has me baffled.

I'm trying to figure out if it makes sense to pay more for VP Motorsport 109 to blend with pump gas because although it costs more than VP 100, I'll use less of it to get a specific octane than if I use VP 100.

 

Try this. Which will give you this result.

 

 

That does it very nicely. Thanks.