15 1/4 acres of land are to be divided into lots of at least 2/3 acres each what is the maximum number of lots that can be created?

Well, if you want the maximum number of splits, then you want to make
each individual split as small as possible. 
That's 2/3 acre.  How many will that give you ?

                  (15 and 1/4) divided by (2/3)

             =      (15.25)  /  (0.666...)  =  22.875 pieces .

The maximum number of 2/3-acre lots you can sell is 22 lots.

Then you have 58.3% of an acre of land left over that you can't sell
because it's less than 2/3 acre.  Sadly, that 58.3% of an acre is just
about the size of the lot that I've been living n for almost 30 years. 
You really know how to rub it in, dontcha !

9/12 is the answer because 3/4 times 3 each is 9/12