Answer:

Perimeter of square with 5cm

P=4a

Perimeter of rectangle with 30cm length and 20cm width

P=100cm

Perimeter of octagon with 8m

P=8a

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My Answer :

Perimeter of square with 5cm :

P = S4

P = 5+5+5+5

P = 20cm

Perimeter of rectangle with 30cm length and 20cm width :

P = (2L) + (2W)

P = (2 × 30) + (2 × 20)

P = 60 + 40

P = 100cm

Perimeter of octagon with 8m :

Octagon = 8

P = 8 + 8 + 8 + 8 + 8 + 8 + 8 + 8 (8 × 8)

P = 64m

Hope I Helped!