
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 bag, there are 15 balls, among which there are $x$ white balls, $2x$ green balls, and the rest are black balls. Player A draws a ball from the bag at random, and wins if it is a green ball. After A puts the ball back into the bag, Player B draws a ball from the bag, and wins if it is a black ball. The game is fair for both Player A and Player B when $x=$ __.

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