Darnell and Stephanie have competing refreshment stand businesses. Darnell's profit can be modeled with the polynomial 7c2 + 120 -250, where is the number of items sold. Stephanie's profit can be modeled with the polynomial 4c2 - 9c - 178. Show your work.

a. Write a polynomial that represents the difference between Darnell's profit and Stephanie's profit.

b. Write a polynomial to show how much they can expect to earn if they decided to combine their businesses.