
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
A school has $120$ students and $4$ teachers. In the first period, each student attends one class, and each teacher teaches one class. The enrollments in the classes are $60, 30, 20,$ and $10$. Calculate $t - s$, where $t$ is the average number of students per class from the perspective of a randomly selected teacher, and $s$ is the average number of students per class from the perspective of a randomly selected student.
A) -15
B) -11.66
C) 0
D) 11.66
E) 15

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