美国数学大联盟竞赛题（四五年级）

A boy and his sister were walking down the street one afternoon when they met a kind old man. When the old man asked them about the size of their family, the boy quickly answered. “ I have as many brothers as I have sisters,” he proudly stated. Not to be left out, the girl added, “ I have three times as many brothers as I have sisters.” Can you tell how many boys and girls in total are there  in their family?

一天下午，一个男孩和他的妹妹在街上散步时遇到了一位善良的老人。当老人问他们的家庭人数时，男孩很快就回答了。他自豪地说:“我的兄弟人数和我的姐妹人数一样多。”女孩补充道:“我的兄弟人数是我的姐妹人数的3倍。”你能说出他们家总共有多少孩子吗?