1) 72 marbles are divided into two portions so that 7 times the smaller portion equals 5 times the bigger portion.Find the number of marbles in the smaller one.
2)The cost of 24 books is $405. Among them,some cost $15 each and all the others cost $20 each.What is the number of books whose cost is $15?
3)There are 42 students in F.1A. The number of boys is 1/3 more than that of girls. Find the numbers of boys and girls respectively.
maths!
2007-05-02 2:15 am
回答 (3)
2007-05-02 2:39 am
✔ 最佳答案
1.Let x be the smaller portion, and number of larter portion is 72-x
5* (72-x) = 7x
360-5x = 7x
12x = 360
x=30
Number of marbles in the smaller one is 30
2.
Let x be the number of book cost $15, then number of book cost $20 = 24-x
15x + (24-x)*20 = 405
15x + 480 -20x = 405
5x = 75
x = 15
There are 15 books whose cost is $15 is
3.
Let x be the number of boys, then number of girls = 42-x
x = (42-x) * (1+ 1/3)
x = 56 – 1.33x
2.33x = 56
x=24
Number of boys = 24, and number of girls = (42-24) = 18
2007-05-12 2:45 am
good!
2007-05-05 7:21 pm
I believe you can finish the homework by yourself
收錄日期: 2021-04-12 17:41:48
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