hmm... Well that is a question you should never really be asking the internet, or trying to make guesswork. Usually Streptococcus infections are tested for a variety of features and then dosages are prescribed based on progression and strain of the bacteria. One thing is for certain though, you follow a doctors dosage and specific medication requirement. If you are asking this question because you think you might have a Strep infection, and you do happen to have left over antibiotics... do not take them, If the medication hasn't been tainted in the first place, it's a good way to get certain antibiotic resistant infections.
Toss them in the trash, see your doctor for a prescription and dosage requirements, and follow through with that current prescription.