Respuesta :

oscar236

Answer:

6 cm.

Step-by-step explanation:

The perimeter = 2(H + W) where H = height and W = width. So we have:

30 = 2(9 + W)

30 = 18 + 2W

2W = 30 - 18 = 12

W = 6 cm.
To find perimeter you need to add all sides of the card. Since the card is 9cm tall, you will add two sides of 9cm which would be 18. Now you subtract 18 from the perimeter (30-18) and you should get 12. Then you divide 12 by two and get the width.
The playing card is 6cm wide.