Answer:
B
Step-by-step explanation:
g(x) - h(x)
= 5x² - 10x + 9 - ( - 3x³ + 5x - 6) ← distribute parenthesis by - 1
= 5x² - 10x + 9 + 3x³ - 5x + 6 ← collect like terms
= 3x³ + 5x² - 15x + 15 → B
