题目

英语翻译
1、One of the most famous puzzles in the math world is“How old is Ann?”Here's one.Ann is now exactly two-fifths of her older sister's age.Conversely,two years ago,Ann was only one-fourth the age of her older sister's age at that time.How old is Ann now?(She's a fairly young child,by the way)
2、You have stealthily raided your small child's piggy bank.You feel slightly guilty as you count the money.You have the same number of dimes and quarters(二角五分硬币）,totaling exactly Yuan 2.45.When you turn honest and put it back,how many of each coin will you need to replace?(Your child keeps a record of how much she puts in and in what denomination(面额）,of course.)

提问时间：2020-07-31

答案

一道数学界最著名的谜题.“安的年龄”安今年年龄是她姐姐2/5,两年前是她姐姐的1/4.
设安今年x岁 她姐姐今年5x/2岁
(x+2)*4=5x/2+2
解得x=4
安今年4岁 姐姐今年10岁
你忐忑地拿走了你孩子的存钱罐.其中一角的硬币和二角五分的硬币一样多.总共2.45元.当你归还时,每种硬币应该归还多少
2.45/(0.1+0.25)=7(枚)
每种硬币归还7枚