
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
Derek set off on his bicycle to visit his sister, traveling at an average speed of $20$ kilometers per hour. When he had gone half the distance to his sister's house, a tire went flat, and he walked the rest of the way at $4$ kilometers per hour. In all, it took him $54$ minutes to reach his sister's house. In kilometers rounded to the nearest tenth, how far did Derek walk?
A) 2.4 km
B) 3.0 km
C) 3.5 km
D) 4.0 km

Present the answer in LaTex format: \boxed{Your answer}
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