
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
In order to promote new energy vehicles, a certain province plans to provide financial subsidies for five consecutive years, starting in the 2017 fiscal year and ending in the 2021 fiscal year. The subsidy for each subsequent year increases over the previous year. In the first three years, the annual increase is a fixed amount of a billion yuan; in the last two years, the subsidy increases at the same growth rate as the previous year. It is known that the planned subsidy for the 2018 fiscal year is 19.8 billion yuan.
(1) If the planned subsidy for the 2019 fiscal year is at least 15% more than that of 2018, determine the range of values for a.
(2) If the total subsidies from 2017 to 2021 are expected to be more than 5.31 times the subsidy for 2018 plus an additional 2.31a billion yuan, calculate the increase rate of the financial subsidies for the last two years.

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