Mark and Brain deposited $510 in total in abank.If Mark deposited 30%less than Brain,how much money did brain deposited?
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2008-05-18 2:52 am
回答 (6)
2008-05-18 5:37 am
✔ 最佳答案
條題目既中文意思係：有一日mark同brain總共存左$510入銀行。
如果甲存既錢比乙少30%，咁乙存左幾多錢入銀行？
設乙存左$a咁多錢。
咁甲就左$(1-30%)a = $0.7a咁多錢入銀行。
佢地總共存左$510咁多錢，即係
a + 0.7a = 510
a(1+0.7) = 510
1.7a = 510
a = 510/1.7
a = 300
所以乙存左300元。
(同時甲存左$510 - $300 = $210咁多錢)
2008-05-18 3:17 am
假設阿Brain存了 $ x 咁多錢入銀行。
那麼，阿Mark就存了$(1-30%)x 咁多錢入銀行，即$0.7x。
他們加埋總共入左 $(x 0.7x)入左銀行，又等於$510。
所以， x 0.7x = 510
1.7x = 510
x = 300
所以，阿Brain存了三佰元入銀行。
2008-05-17 19:22:39 補充：
「x 0.7x = 510」→ 「x ┼ 0.7x = 510」
不好意思，一時忘了Yahoo知識plus的答案編輯器，若然兩邊留有空格，總會把人家的加號給吃掉。
那麼，阿Mark就存了$(1-30%)x 咁多錢入銀行，即$0.7x。
他們加埋總共入左 $(x 0.7x)入左銀行，又等於$510。
所以， x 0.7x = 510
1.7x = 510
x = 300
所以，阿Brain存了三佰元入銀行。
2008-05-17 19:22:39 補充：
「x 0.7x = 510」→ 「x ┼ 0.7x = 510」
不好意思，一時忘了Yahoo知識plus的答案編輯器，若然兩邊留有空格，總會把人家的加號給吃掉。
2008-05-18 3:15 am
let Brain deposited $ y
y+(1-30%)y=510
1y+0.7y=510
(1+0.7)y=510
1.7y=510
y=300
so Brain deposited $300
y+(1-30%)y=510
1y+0.7y=510
(1+0.7)y=510
1.7y=510
y=300
so Brain deposited $300
參考: me
2008-05-18 3:09 am
let mark deposited x and brain deposited y
x+y=510....(*)
(y-x)/y=0.3....(#)
sub*into#
(510-x)-x=0.3(510-x)
510-2x=153-0.3x
357=1.7x
x=210
y=510-210
=300
so brain deposited $300
x+y=510....(*)
(y-x)/y=0.3....(#)
sub*into#
(510-x)-x=0.3(510-x)
510-2x=153-0.3x
357=1.7x
x=210
y=510-210
=300
so brain deposited $300
參考: me
2008-05-18 3:00 am
let $ x be the amount of money brain deposited.
----------> (1-30%)x + x = 510
1.7x = 510
x = 300
so, the amount of money mark desposited
= 300 x (1-30%)
= 300x 0.7
= 210
or the amount of money mark desposited
= $ 500-300
= $ 210
----------> (1-30%)x + x = 510
1.7x = 510
x = 300
so, the amount of money mark desposited
= 300 x (1-30%)
= 300x 0.7
= 210
or the amount of money mark desposited
= $ 500-300
= $ 210
參考: myself
2008-05-18 2:59 am
let x be the money that brain deposite
x(0.7)+x=510
x=300
i.e Brain deposited $300
x(0.7)+x=510
x=300
i.e Brain deposited $300
參考: 自己
收錄日期: 2021-04-13 16:34:58
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080517000051KK02427