Answer is 36.
20 * 80/100 = 16
20+16=36
Notice the tickmark on the angles, those angles are equal to each other.
now, notice the angle at the very top, the large triangle is really sharing it with smaller-inscribed triangle, and therefore is equal on both triangles.
therefore, the larger triangle, is similar with smaller-inscribed triangle by AA.
what the dickens does that mean?
F. 24, this is because if you split the bigger square in half you’ll get 6 and perimeter is the addition of all sides. So 6+6+6+6=24

Refer to the attachment for step by step explaination.