Which expression is equivalent to 9x3+5x+7+6x3+5x2-5?
15 x 3 + 10 x 2 + 2
15 x 6 + 5 x 2 + 5 x + 2
15 x 3 + 5 x 2 + 5 x + 2
15 x 6 + 5 x 2 - 5 x - 35
