
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
$ABCD$ is a rectangle whose area is 20 square units. How many square units are contained in the area of trapezoid $EFBA$ where $E$ and $F$ are points on $AD$ and $BC$ respectively, such that $AE = 1$ unit and $BF = 1$ unit?

[asy]
size(4cm,4cm);
for(int i=0; i < 5; ++i){
for(int k=0; k < 6; ++k){
draw((0,i)--(5,i));
draw((k,0)--(k,4));
} }
draw((0,0)--(1,4));
draw((4,4)--(5,0));
label("$A$",(0,0),SW);
label("$B$",(5,0),SE);
label("$C$",(5,4),NE);
label("$D$",(0,4),NW);
label("$E$",(1,4),N);
label("$F$",(4,4),N);
[/asy]

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