20分一條好簡單既方程

🎓 學業台教學

2009-05-01 7:00 pm

解以下的方程plz~

x/3-(20-x)/7=10

更新1:

仲有一題: An amount of $830 is shared among 35 children.Each child of the age 10 years or above can get $25 and each child of the age below 10 can get$16. How many children are of age 10years or above?

回答 (3)

用戶7639

2009-05-01 7:53 pm

✔ 最佳答案

x/3-(20-x)/7=10
7x-3(20-x)=210
7x-60+3x=210
10x=270
x=27//

Let x be the number of children of the age 10 years or above.
then 35-x be the number of children of the age below 10 。
25x+10(35-x)=830
25x+350-10x=830
15x=480
x=32
∴The number of children of the age 10 years or above=32//

👍 0 👎 0

用戶236780

2009-05-04 1:29 am

21(x/3-(20-x)/7)=21*10

7x-3(20-x)=210

7x-60+3x=210

9x=270

x=30

參考: -----------------------------------------------------

👍 0 👎 0

陳昇遠

2009-05-01 7:03 pm

x/3-(20-x)/7=10

21(x/3-(20-x)/7)=21*10
7x-3(20-x)=210
7x-60+3x=210
9x=270
x=30

2009-05-01 11:05:39 補充：
為了消去分母所以等式兩邊乘上 3&7 的 L.C.M. 21

👍 0 👎 0

收錄日期: 2021-04-23 20:37:22
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090501000051KK00453

檢視 Wayback Machine 備份