we know that
15 1/4 acres-----------> (15*4+1)/4-----> 61/4 acres
[number of lots]=(61/4)/(2/3)----> (61*3)/(4*2)---> 183/8----> 22.875
22.785-----> 22 7/8
we know that
7/8--------> multiply by 3-------> 21/24
2/3-------> multiply by 8-------> 16/24
21/24-16/24-------> 5/24
so
22 7/8 is equals to--------> 22 21/24----> 22 (16/24+5/24)
the maximum number of lots that can be created are 22+1-----> 23 lots
and there is a remnant of 5/24