If you draw out the polygon with the vertices given, you'll see a trapezoid with one base of 6 units long, one base of 4 units long and a height of 4 units.
Using the formula for area of a trapezoid : h(b1 + b2)/2
h is the height, b is the base
After inputting your numbers into the formula you get, 4(4+6)/2
Which comes out to be 4(10)/2 or 40/2
Which will get you the answer, 20.
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