this is for introduction to polynomials

10. Sales: PDQ Tennis Shoe Co. follows a profit model of P= 3x -15x + 2, where P is the profit in hundreds of dollars after selling x hundred pairs of tennis shoes. Find each of the profits for PDQ after selling 100 pairs, 500 pairs and 1000 pairs of tennis shoes. What does a negative value for profit represent? Writing & Thinking 11. Tony was classifying expressions for a homework assignment. He said that 7y + 12y - 3 was a polynomial. Was he correct or not? Justify your answer. 12. Jeanne thought that 10a - 9 + 6a was in descending order. Explain Jeanne's error and what the correct descending order should be