Answer:
A 20.8 cm
Step-by-step explanation:
The perimeter of a rectangle is
P = 2(l+w)
We know the length is 8cm and the width is 24mm
The need to be the same units to add them together
Change 24 mm * 1cm/10 mm = 2.4 cm
Substitute 8 cm for l and 2.4 cm for w
P = 2(8+2.4)
P = 2 (10.4)
P = 20.8 cm
