Solve the problem using sequential reasoning steps.

FORMAT RULES (follow exactly):
- Label each reasoning step as [R1], [R2], [R3], etc.
- Do not skip steps. 
- After all reasoning steps, output your final answer on a separate line.

OUTPUT FORMAT:
[Question]: <restate the question>
[R1]: <first reasoning step>
[R2]: <second reasoning step>
...
[Rn]: <final reasoning step>
[Answer]: <your final answer>

EXAMPLE:
[Question]: If a train travels 60 mph for 2.5 hours, then 80 mph for 1.5 hours, what is the average speed for the whole trip?
[R1]: Distance in first segment: 60 × 2.5 = 150 miles.
[R2]: Distance in second segment: 80 × 1.5 = 120 miles.
[R3]: Total distance: 150 + 120 = 270 miles.
[R4]: Total time: 2.5 + 1.5 = 4 hours.
[R5]: Average speed: 270 / 4 = 67.5 mph.
[Answer]: 67.5 mph

Now solve:
{question}