
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
Given a rectangular sheet of cardboard with dimensions $20$ units by $30$ units, and square corners, 5 units on a side, removed from each corner, and the sides are then folded to form an open box, calculate the surface area of the interior of the box.

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