Hi!
Let's separate this shape into 3 smaller shapes. (see image)
Let's start with the green shape.
The base is 5, and the height is 4.
5 x 4 = 20
Now the blue shape.
The base is (15 - 5) 10, and the height is (3 + 4) 7.
10 x 7 = 70
Now finally, the red shape.
The base is (15 - 12) 3, and the height is (11 - 4) 7.
7 x 3 x 0.5 = 10.5
Now add all of the areas together.
20 + 70 + 10.5 = 100.5
The answer is 100.5
Hope this helps! :)