Let $$x$$ be the number of cars.  $$2x+4x=48$$  $$6x=48$$  $$x=8$$ 
There is an equal number of motorcycles and cars in the parking lot. They have $$48$$ wheels in total. How many cars are there in the parking lot? 
A: $$8$$ 
B: $$12$$ 
C: $$16$$ 
D: $$24$$ 