Answer:
39 inches
Explanation:
All of the sides are the same length because all of the angles are equal
21 - x = 2x - 3 Set two sides equal to each other and solve for x. Add x to both sides
21 = 3x - 3 Add 3 to both sides
24 = 3x Divide both sides by 3
x = 8
Substitute in 8 for x to find the value of a side
2x - 3
2(8) - 3
16 - 3
13
Each side length is 13
3 x 13 = 39