$10+10+10=30$ 
There are some ducks and chickens in a farm. The number of chickens is $10$ more than ducks.The number of ducks is half the number of chicken. How many ducks and chickens are there in the farm?  ~ 
A: $26$ 
B: $$30$$ 
C: $$33$$ 
D: $$39$$ 
E: $$40$$ 