Andy spent $$5$$ dollars on $$15$$ biscuits. How much would it cost if Andy bought six more of them? (adapted from $$2008$$ Math kangaroo Problems, Level $$1-2$$, Question \#$$13$$) 
选项为:A:$$6$$  B:$$7$$  C:$$8$$  D:$$9$$  请回答其中一个选项.