Answer:
b. 10a³ - 11a - 3
Step-by-step explanation:
1. Expand 3(a³ - 2a - 5)
= 3a³ - 6a - 15
2. Add 7a³ - 5a + 12 and 3a³ - 6a - 15
7a³ + 3a³ = 10a³
-5a + -6a = -11a
12 + -15 = -3
3. Answer: b. 10a³ - 11a - 3
