Help anyone can help me do this question,I will mark brainlest.

Answer:
Q.8 . circumference of circle =2×pi×r
157cm =2×3.14×r
157cm =6.28×r
157cm/6.28 =r
25cm =radius
Q.9. circumference of circle=2×pi×r
99cm =2×22/7×r
99cm =44/7×r
(99cm×7)/44=r
15.75cm =r
2×15.75cm =diameter
31.5cm=diameter