Answer: The area common to both triangle is 31.77 sq. cm.
Step-by-step explanation:
Since we have given that
30-60-90 triangles are placed.
So, the ratio of sides would be

Since Hypotenuse = 12 cm
So, it becomes,

So, Base would be

and Perpendicular would be

So, Area common to the both triangles would be

Hence, the area common to both triangle is 31.77 sq. cm.
Number 28 would be y= -52x+148