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Luv2Teach

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