So if "Double my tens digit" is written as 2x and "to get my ones to double mean" just translates to = 2y ("mean" is another word for average, but since we're talking about the "ones digit", then this is just one number... And double the average of a single number, is just double that original number) and "I'm less than 50" rounds it off with < 50, then you can rewrite this as:

2x2y (as one single number) < 50

So you could use 1 in place of x, and this would give you:

2 = 2 < 50 which is true.

That would make the number 11 or 22.

I think these are the only possible answers