75.
Explanation: from 3 to 12, you add 9, and then double the 12 to get to 24, and then add 9 again to get to 33, and double it to get 66, so the pattern is to add 9 and then double.
Answer:
is c
Step-by-step explanation:
Answer:
b = c - a - D
Step-by-step explanation:

Folded mountain with waves, twists, and turns. I believe because the article stated it was gradual and various patterns were formed.