
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 line with slope of $-3$ intersects the positive $x$-axis at $A$ and the positive y-axis at $B$. A second line intersects the $x$-axis at $C(10,0)$ and the positive y-axis at $D$. The lines intersect at $E(5,3)$. What is the area of the shaded quadrilateral $OBEC$?

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