I think one thing is paint but what on earth are you mixing it with? It looks like "fbetrol" or "Ploetrol"; I thought "petrol" at first but I can't think of any reason why you would mix paint with petrol.
I momentarily thought "petrol" too, but a quick search for "Floetrol", which I'd never heard of, made it clear (and showed that 2:1 is the maximum ratio recommended). It apparently con
trols the
flow of paint.
I would recommend the "parts" approach two people have now recommended (more or less), but it can also be solved by basic algebra, so I may as well show how to start that.
Suppose you use x ounces of paint. At a 2:1 ratio, how much Floetrol would you use?
How much of the mixture would you get?
Set that expression equal to the desired amount, 6 ounces, and solve for x.
(In the other method, our x turns out to be the size of a "part".)
By the way, any of these methods assumes that the volumes add, which is not always true of solvents. So it's possible that you'd get a little less than 3 fluid ounces if you mixed 2 of Floetrol and 1 of paint. We'll ignore that, as we have no control over it.