2010年第11届上海中环杯小学中年级三年级竞赛第11题12分
一个四口之家，由爸爸、妈妈、大儿子和小儿子组成，他们的年龄之和是$$68$$岁，爸爸比妈妈大$$2$$岁．$$3$$年前，这个家庭的成员的年龄之和是$$57$$岁；$$5$$年前，这个家庭的成员的年龄之和是$$52$$岁．请问这个家庭每个成员现在的年龄各是多少岁？  There are four members in a family, dad, mom, elder brother, and little brother. Their sum of the ages this year is $68$, and dad is $2$ years older than mom. $3$ years ago from now, their sum of the ages was $57$; $5$ years ago from now, their sum of ages was $52$. How old is dad this year? 
拓展思维->能力->逻辑分析 Overseas Competition->知识点->应用题模块->年龄问题
$$3$$年前，四人年龄之和是$$68-3\times 4=56$$（岁），但实际上是$$57$$岁，这说明$$3$$ 年前小儿子还没有出生，是$$2$$年前出生的，所以小儿子今年是$$2$$岁．则其余$$3$$人年龄之和是$$66$$岁．$$5$$年前，$$3$$人的年龄和应该是$$66-5\times 3=51$$（岁），但实际上是$$52$$岁，这说明$$5$$年前大儿子还没有出生，是$$4$$年前出生的，所以大儿子今年是$$4$$岁．则爸爸妈妈的年龄和是$$62$$岁，而爸爸比妈妈大两岁，所以爸爸今年$$32$$岁，妈妈今年$$30$$岁．     $3$ years ago from now, their sum of ages should be $$68-3\times 4=56$$ but actually it was $57$, which means the little brother was not born $3$ years ago. He was born $2$ years ago. Thus, the little brother this year is $2$ years old and the sum of the other three members this year is $68-2=66$ years old.     $5$ years ago from now, the sum of the three members ages should be $66-5\times 3=51$ but actually it was $52$, whcih means the elder brother was not born $5$ years ago. He was born $4$ years ago. Thus, the elder brother is $4$ years old this year.     Thus, the sum of ages of mom and dad this year is $66-4=62$. Dad is $2$ years older than mom, which means dad is $32$ years old and mom is $30$ years old. 