The masons built a deck in their backyard.

what is the area of the deck? (no units)

Take the area of the rectangle as a whole and subtract the triangle piece.
We know the dimensions of the triangle are 3x4 so you can multiply it out using the formula to find the triangle's area to get 6.
Then you calculate the area of the whole rectangle. 10x12=120.
Finally subtract the triangle from the rectangle. 120-6=114.
The Area of the deck is 114.

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