Final answer:
Megan bought 4 bottles of Dr. Pepper based on the problem's given algebraic equation. However, this answer is not listed in the provided options, suggesting a possible error in the formulation of the question or the options.
Step-by-step explanation:
The question is a simple algebra problem where we have to determine the number of bottles of Dr. Pepper Megan bought. Megan purchased 12 bottles of Mountain Dew. Let the number of Dr. Pepper bottles be 'd'. The total number of bottles is said to be four times the Dr. Pepper bottles, meaning 12 + d = 4d. To find 'd', we can rearrange the equation to solve for d:
4d - d = 12
3d = 12
d = 12 / 3
d = 4
Since the question provides options a) 3 b) 6 c) 9 d) 12, and '4' is not one of the options, we can conclude there might have been an error in the problem or the options given. Megan would have bought 4 bottles of Dr. Pepper if the provided information is correct.