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👨🏻‍🏫 學術台數學

用戶11587

2007-10-30 4:09 am

Three years ago, Emily`s father was 5times as old as she. If the sum of their present age is 108, find Emily`s present age .
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回答 (6)

雞尾包

2007-10-30 4:22 am

✔ 最佳答案

Emily`s present age = x
Three years ago, Emily`s father age = 5(x - 3)
Emily`s father present age = 5(x - 3) + 3
5(x - 3) + 3 + x = 108
5x - 15 + 3 + x = 108
6x = 120
x = 20
Emily`s present age is 20

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Hide and Seek

2007-10-30 4:31 am

Analysing:
The age of Emily's father 3 years ago=5(x-3)
The present age of Emily's father=5(x-3)+3
The present age of Emily's father also equals to (108-x)

Let x years old be Emily's present age
5(x-3)+3=108-x
5x-15+3=108-x
6x=120
x=20

Therefore, Emily's present age is 20 years old.

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WONG WK

2007-10-30 4:25 am

設 Emily是ａ。

　　　　　　　５ａ＝１８０
　　　　　５ａ／５＝１８０／５
　　　　　　　　ａ＝３８

Emily是３０。

係咪咁？？唔係幾睇得明英文～～

2007-10-29 20:25:47 補充：
３８．．．．．．．．．．．．．．

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用戶46949

2007-10-30 4:24 am

Let Y be the age of Emily's present age.

( Y -3 ) x 5 +3 be is Emily's father present age.

(Y-3) x 5 +3 + Y = 108
5Y - 15 +3 +Y =108
6Y - 12= 108
6Y = 120
Y=20
Emily is 20 years old.

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[匿名]

2007-10-30 4:20 am

應該係
108/6=18 -.-

2007-10-29 20:21:52 補充：
睇小左3 year ago- -'108/6 3=21

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