
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
An isosceles right triangle with legs of length 10 is divided into 25 smaller congruent triangles. If the shaded area consists of 15 of these triangles, calculate the shaded area.
A) 20
B) 25
C) 30
D) 35
E) 40

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