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.
The 7 miles and 24 miles make up two "legs" of a right triangle. The third side (or hypotenuse) is the distance between the towns. distance^2 = 7^2 + 24^2 distance^2 = 49 + 576 distance^2 = 625 distance = square root of 625 or 25
