maths(2)
2011-07-30 6:07 am
The ratio ofthe number of marbles owned by Susan to the number of marbles owned by Teresais 5:2. Susan has n marbles. If Susan gives 18 of her marbles to Teresa, bothof them will the same numbers of marbles. Find n.
回答 (3)
2011-07-30 8:15 am
✔ 最佳答案
Let Susan has n marbles and Teresais has y marblesThen n : y = 5 : 2
Also n - 18 = y + 18
n = y + 36
So, (5/2)y = y + 36
(3/2)y = 36
y = 24; n = 60
2011-07-31 1:52 am
let Teresais has a marbles.
n/a=5/2
5a=2n
a=(2/5)n
Teresais has (2/5)n marbles.
n-18=(2/5)n+18
n-(2/5)n=18+18
(3/5)n=36
n=60
n/a=5/2
5a=2n
a=(2/5)n
Teresais has (2/5)n marbles.
n-18=(2/5)n+18
n-(2/5)n=18+18
(3/5)n=36
n=60
參考: me
2011-07-30 7:03 am
Let Teresa has m marbles.
n : m = 5 : 2
5m = 2n . . . . (1)
If Susan gives 18 of her marbles to Teresa,
then Susan has (n-18) marbles and Teresa has (m+18) marbles.
n-18 = m+18
m = n-36 . . . . . (2)
Substitute (2) into (1):
5(n-36) = 2n
5n-180 = 2n
3n = 180
n = 60
n : m = 5 : 2
5m = 2n . . . . (1)
If Susan gives 18 of her marbles to Teresa,
then Susan has (n-18) marbles and Teresa has (m+18) marbles.
n-18 = m+18
m = n-36 . . . . . (2)
Substitute (2) into (1):
5(n-36) = 2n
5n-180 = 2n
3n = 180
n = 60
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