Answer:

29d³ - 11d² - d + 33

Step-by-step explanation:

(17d³ - 2d² + 15)- (-12d³ + 9d² + d - 18)

17d³ - 2d² + 15 + 12d³ - 9d² - d + 18

17d³ + 12d³ - 2d² - 9d² - d + 15 + 18

= 29d³ - 11d² - d + 33

Hope this helps :)