The answer is I believe: 21
What 3D figure/shape is it?
Answer:

Step-by-step explanation:
The area of an equilateral triangle with side length
is equal to
. Since the perimeter is 24 units and there are three equal sides to an equilateral triangle, each side is
units.
Substituting in this value, we get:

20.50 * 0.8 = $16.40
16.40 * 0.4 = $6.56
Final selling price = $6.56