maths quickly!!
2007-03-18 11:58 pm
The difference of two numbres is four-fifths of their sum,and the bigger number exceeds six times the smaller number by 21,find the number.
回答 (2)
2007-03-19 12:06 am
✔ 最佳答案
x-y=4/5(x+y) _1x=6y+21 _2
6y+21-y=4/5(6y+21+y)
5y+21=4/5(7y+21)
25y+105=28y+84
3y=21
y=7
x=6(7) +21
= 63
參考: me
2007-03-19 12:07 am
Let the bigger number be x and the smaller number be y.
x - y = 4/5 ( x+y ) ... (i)
x = 6y+21 ...(ii)
Sub (ii) into (i) ,
6y+21-y = 4/5 (6y+21)
25y+105 = 28y+84
21=3y
y=7
so x = 6(7)+21 = 63
x - y = 4/5 ( x+y ) ... (i)
x = 6y+21 ...(ii)
Sub (ii) into (i) ,
6y+21-y = 4/5 (6y+21)
25y+105 = 28y+84
21=3y
y=7
so x = 6(7)+21 = 63
參考: me
收錄日期: 2021-04-25 20:19:45
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https://hk.answers.yahoo.com/question/index?qid=20070318000051KK02941