Which one of these numbers is not like the others 21,15,6,16,and27

Write the equation in general quadratic form: plz !

If a suspect is in possession of 20 grams of cocaine how many ounces does he possess what will the charge be

Ireally need ! if a musician uses his credit card to pay for a new violin that costs $2,900 and does not pay on it until the second month, what will the 3.35% monthly interest charge be at the end of the first month? show your work or explain how you got your answer.