Answer:
Correct option: second one -> 21 square units
Explanation:
First let's find the side of the square.
We can find this side finding the distance between two points of the square, using the formula:

Using points (1,4) and (4,7), we have:



So the area of the square is:


Now, let's find the three sides of the triangle:
points (5,8) and (7,8):

points (7,8) and (8,5):

points (8,5) and (5,8):

The area of the triangle can be calculated using the formula:

Where p is the semi perimeter of the triangle:

So the area is:

Now, adding both areas, we have:
Total area = 18 + 3 = 21 square units
Correct option: second one