Answer :

12-6=6 
So Judy has 6 birds
So Cora and Judy have equal amounts of Birds
luana
[tex]x-\ Cora\\ y-\ Judy\\\\ x+y=12\\ x+6=y\\\\ x+x+6=12\\ 2x+6=12\ \ | subtract\ 6\\ 2x=6\ \ \ | divide\ by\ 2\\ x=3\\ y=3+6=9\\\\ 9\ birds\ belong\ to\ Judy.[/tex]