When we started walking down the mountain, Dad said, ‘ Look at those black clouds !’ It started raining. ‘ I can’t see,’ I said. I was afraid. ‘ It’s OK,’ said Dad. ‘ We have Sam with us. He can help us.’ Dad was right. Sam walked in front of us and found my grandparents’ house again. We had a hot dinner and I gave Sam his favorite food. ‘ Thank you, Sam,

cho một hình tròn có chu vi bằng 163,28cm . tính diện tích hình tròn đó