
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
According to a survey, a bicycle parking lot had a parking volume of 2000 bicycles on a certain Sunday. The parking fee for variable-speed bicycles was 0.8 yuan per bicycle per time, and the parking fee for ordinary bicycles was 0.5 yuan per bicycle per time. If the number of times ordinary bicycles were parked is x, determine the function relationship of y with respect to x, where y is the total parking fee income.

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