The perimeter of this shape is 77 cm.
What is the length of side d?

Answer:
d - 20.4 cm
Step-by-step explanation:
The perimeter by definition is the sum of all the sides of a figure. We have 3 of the 4 sides and we know the sum of them is 77:
14.4 + 19.5 + 22.7 + d = 77 and
56.6 + d = 77 so
d = 20.4