
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 a basket, there are red marbles and green marbles. Initially, the ratio of red to green marbles is 5:3. If I remove 20 red marbles and add 40 green marbles, the new ratio of red to green marbles becomes 1:5. How many red marbles were in the basket at the beginning?

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