
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
Due to the needs of epidemic prevention and control, Xiaoming's father bought $3$ thermometers at a unit price of $a$ yuan each, and $b$ masks at a unit price of $1$ yuan each, spending a total of ______ yuan. (Express using algebraic expressions involving $a$ and $b$).

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