Solve 2 math questions and show steps if needed

Recall the definition of a polynomial expression. find two polynomial expressions whose quotient, when simplified,is. use that division problem to determine whether polynomials are closed under division. then describe how theother three operations-addition, subtraction, and multiplication-are different from division of polynomials.

Solve the system of equations. y= 2x y= x^2 - 15

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?