Find the circum of each circle. Use 3.15 for pi

13.) Diameter = 10

15.) Diameter = 50

Use the formula for circumference. In this case pi will be 3.15 and we will be using half of the diameters for the radius.

2 (3.15) (radius)

13) 2 (3.15) (5)

Circumference=31.5

14) 2 (3.15) (25)

Circumference=157.5