The area of the figure is 71 in².
The area can be found by noticing that the figure is a rectangle with a triangular section taken out from the corner (see attached figure). You can use this information to easily find the shape's area.
To find the area of the original rectangle, before the triangle was taken away, multiply its length and width together:
This gives you the area of the rectangle, in in².
Next, we need to find the area of the small triangle. Using the information given, you can find that this triangle has side lengths of 4 and 5. The area of a triangle can be found by multiplying its base times its height, then dividing this value by two. Doing so for this triangle gives us:
in².
Now that we know the areas of both shapes, simply subtract the area of the triangle from the area of the rectangle: 81 in² - 10 in² = 71 in², which is the area of the entire shape.