1. In a bookstore , the number of Chinese books is 50 more than twice the number of English books . If there are 350 Chinese books , find the number of English books in the bookstore .
2. Lok is 5 years younger than his sister, Yau .The age of their father is 4 times the age of Yau .If their father is 40 years old , find the age of Lok .
3. Miss Chan bought a bag of candies . She first took 5 candies and then evenly distributed the remaining candies to 3 children . If each child got 7 candies , find the original number of candies in the bag .
4. In a test , 3 marks will be given for each correct answer and 2 marks will be deducted for each wrong answer . If Chris gives wrong answers for 11 questions and he gets 50 marks , find the number of questions he gives correct answer.
中一數學方程
2013-08-13 9:24 pm
回答 (3)
2013-08-13 10:13 pm
✔ 最佳答案
1.Let n be the number of English books.
350 - 2n = 50
2n = 300
n = 150
Hence, the number of English books = 150
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2.
Let k and u be the ages of Lok and Yau respectively.
k = u - 5 ...... [1]
4u = 40 ...... [2]
From [2] :
u = 10
Put u = 10 into [1]
k = 10 - 5
k = 5
Hence, the age of Lok = 5
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3.
Let n be the number of candies.
(n - 5) / 3 = 7
n - 5 = 21
n = 26
Hence, the number of candies = 26
=====
4.
Let n be the number of questions he gives correct answer.
3n - 2(11) = 50
3n - 22 = 50
3n = 72
n = 24
Hence, the number of questions he gives correct answer = 24
參考: andrew
2013-08-13 10:55 pm
Man wai, very good try.
Do you see the difference between your answers and Andrew's answers?
Try to learn from him as well.
Cheers! :)
Do you see the difference between your answers and Andrew's answers?
Try to learn from him as well.
Cheers! :)
收錄日期: 2021-04-13 19:39:43
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20130813000051KK00180