
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
Xiao Ming recorded the number of phone calls and their durations in May of this year, and listed the frequency distribution table as follows:

| Duration $x$/min | $0 < x \leqslant 5$ | $5 < x \leqslant 10$ | $10 < x \leqslant 15$ | $15 < x \leqslant 20$ |
|------------------|---------------------|----------------------|-----------------------|-----------------------|
| Frequency (calls)| $20$                | $16$                 | $9$                   | $5$                   |

The frequency of calls with a duration not exceeding $15$ minutes is ____.

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