$27-20=7$  $7+7=14$  $27-14=13$ 
There were $20$ ducks, pigs, and sheep in total in Sam\textquotesingle s farm. After Sam bought some new sheep, the number of sheep has doubled. There are $27$ ducks, pigs, and sheep in total. Originally, how many ducks and pigs were there? 
Options:
[1] $$13$$ 
[2] $$7$$ 
[3] $$10$$ 
[4] $$14$$ 
[5] $$16$$ 