
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
Determine the area of the shaded portion shown in the diagram below. Present your final answer rounded to the nearest whole number.

[asy]
draw((0,0) -- (4,0) -- (4,4) -- (0,4)--cycle) ; draw((4,0)-- (16,0) -- (16,12) -- (4, 12)--cycle);

label ( "4 cm", (0,2), W); label ( "4 cm", (2 ,0), S);
label ( "12 cm", (4+12/2 ,0), S);label ( "12 cm", (16 ,12/2), E);
draw( rightanglemark( (4, 12) , (4,0) , (16,0) ,31 ));
draw( rightanglemark( (4,0), (16,0), (16, 12) ,31 ));
draw( rightanglemark( (4,0), (4,4), (0, 4) ,21 ));
draw( rightanglemark( (4,4), (0, 4) , (0,0) ,21 ));
draw( (0,0) -- (16, 12));
fill( (4, 12/4) -- (16, 12) -- (4,12)-- cycle , darkgray); draw( rightanglemark( (16,12) , (4, 12), (4,0), 31 )); [/asy]

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