Answer:
6
Step-by-step explanation:
Remark
This is one of those things that when you see it, you think that really is something.
The trick is to subtract a smaller right triangle from a larger one.
The base for both triangles is 4 (going from where the right angle is to your right where the lines of the red enclosure meet.
Calculations
The height of the larger triangle is 8
The height of the smaller triangle is 5
Area_L = 1/2 8 * 4 = 1/2 * 32 = 16
Area_S = 1/2 5 * 4 = 1/2 * 20 = 10
Red area = 1/2 * 32 - 1/2*20 = 16 - 10 = 6 units
