Mike has $7y+1$ cans of coke. He gives his friends $$x$$ cans of coke. And he takes one out. How many cans of coke does he have left? 
选项为:A:$$7y + 1$$  B:$$7y + 1 -x$$  C:$$7y-x$$  D:$$7y$$  请回答其中一个选项.