
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
Let the function $f(x) = |x - a| + 5x$.  
(1) When $a = -1$, find the solution set of the inequality $f(x) \leq 5x + 3$;  
(2) If $f(x) \geq 0$ when $x \geq -1$, find the range of values for $a$.

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