一到英语竞赛智力题,When David is twice as old as he is now he will be four times as old as his daughter Jane will be in five years time.If in 1990,he was four times as old as his daughter; in what year was she born?答案是1983年,我求到

一到英语竞赛智力题,When David is twice as old as he is now he will be four times as old as his daughter Jane will be in five years time.If in 1990,he was four times as old as his daughter; in what year was she born?答案是1983年,我求到
一到英语竞赛智力题,
When David is twice as old as he is now he will be four times as old as his daughter Jane will be in five years time.If in 1990,he was four times as old as his daughter; in what year was she born?答案是1983年,我求到的是1975年,不理解

一到英语竞赛智力题,When David is twice as old as he is now he will be four times as old as his daughter Jane will be in five years time.If in 1990,he was four times as old as his daughter; in what year was she born?答案是1983年,我求到
你漏了个 four years ago,我的神啊
when david is twice as old as he is now he will four times as old as his daughter Jane will be in five years time .If in 1990,four years ago,he was four times as old as his daughter ,in what year was she born?
当david的年龄是现在年龄的两倍的时候,他的年龄是他的女儿jane五年后年龄的四倍.如果在1990年,四年前,他的年龄是他女儿年龄的四倍,那么jane是什么时候出生的?
设现在david年龄x,他的女儿jane的年龄y,则2x=4(y+5)
1990年是4年前,则现在是1994年
所以根据第二句话有：x-4=4(y-4)
则根据以上两个方程求出y=11,x=32
则在1994年也就是现在他爸爸32岁,他女儿11岁,
则四年前 他女儿11－4＝7岁
则他女儿出生在1990－7＝1983年

这道题其实是一道老题目，上世纪90年代就出现的题目。两个答案都对，解释如下：
文中第一句话意思是：David现在年龄的2倍等于他女儿Jane从现在起再过5年的年龄的4倍。
文中第二句话的意思是：在1990年时，David的年龄是他女儿的4倍。
答案1983的情况：David在21岁时生女儿(即David比女儿大21岁)。
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这道题其实是一道老题目，上世纪90年代就出现的题目。两个答案都对，解释如下：
文中第一句话意思是：David现在年龄的2倍等于他女儿Jane从现在起再过5年的年龄的4倍。
文中第二句话的意思是：在1990年时，David的年龄是他女儿的4倍。
答案1983的情况：David在21岁时生女儿(即David比女儿大21岁)。
现在(1994年) David是32岁，女儿11岁。32×2=(11+5)×4；
David在1990年时28岁，女儿7岁。28=7×4
1990年时女儿7岁，所以女儿1983年生（这道题的“现在”是1994年）。
答案1975的情况：David在45岁时生女儿(即David比女儿大45岁)。
现在(2010年) David是80岁，女儿35岁。80×2=(35+5)×4；
David在1990年时60岁，女儿15岁。60=15×4
1990年时女儿15岁，所以女儿1975年生（这道题的“现在”是2010年）。

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