Please help me to do Maths, thx!

2007-04-16 6:33 am
Mary has 53stamps and Jack has 70stamps. In order to make the number of Mary's stamps twice that of Jack's, how many stamps should Jack give to Mary?

回答 (7)

2007-04-16 6:40 am
✔ 最佳答案
Let X be the number of stamp that Jack need to give to Mary.

53+x = 2 * (70-x)
53+x = 140 - 2x
 3x = 87
 x = 29

So, Jace need to give may 29 stamps.


2007-04-16 09:15:21 補充:
最後果句打錯字,應該係:So, Jack needs to give Mary 29 stamps.
2007-04-16 6:52 am
Assume X is no. of stamps Jack should give to Mary
70 - X = (53+70)/3
X = 70 - 41
X = 29

Jack should give 29 stamps to Mary, then Mary will have 82 stamps and Jack will have 41 stamps.
參考: me
2007-04-16 6:47 am
Let x be the stamps of Jack that after Mary gave the stamps to Mary.

( 53 + 70 ) / 3 = x
123 / 3 = x
x = 41

Hence, the stamps of Jack is 41 and the stamps of Mary is 41* 2 = 82.

Hence, the stamps that Jack should give to Mary is 70 - 41 = 29.
參考: By me.
2007-04-16 6:46 am
Let y be the number of stamp that Jack give to Mary

53+y = 2(70-y)
53+y = 140-2y
3y = 87
y = 29

Ans: Jack needs to give 29 stamps tp Mary.
2007-04-16 6:44 am
Logical thinking:
(53+70)/3x2-53=29

In formula:
x = no. of stamps Mary has (53)
y = no. of stamps Jack has (70)
z = no. of stamps Jack gives Mary to get the result

by substituting into the formula 2(x+z) = y-z, z=29.
參考: me
2007-04-16 6:42 am
29
Total stamps=53+70=123
Since no. of stamps of Mary's : no. of stamps of Jack's = 2 : 1
So, no. of stamps of Mary's = 2/(2+1)*123
= 82
So, no. of stamps of Mary's received from that of Jack's =82-53
= 29
參考: Myself
2007-04-16 6:41 am
find the total number of stamps first: 53+70=123
In order to make the number of Mary's stamps twice that of Jack's,the ratio should be 1:2(jack:mary) that's mean the total number should divied by3parts(1+2), and mary will get two parts of it, jack get 1 parts. This can make the number of Mary's stamps twice that of Jack's.

[(53+70)/3*2]-53=29


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