Donna has three types of coins:$1 coins, $2 coins and $5 coins.
The number of $1 coins is three tines that of $2 coins.
The number of $2 coins is $5 coins more than the number of $5 coins.
The total value of Donna's coins is $325.
How many $2 coins does she have?
呢題數點做呀
2007-10-29 6:52 am
回答 (2)
2007-10-29 7:10 am
✔ 最佳答案
1x + 2y + 5z = 325x = 3y
y = 5 + z
y = ?
1[3(5+z)] + 2(5+z) + 5z = 325
15 + 3z + 10 + 2z + 5z = 325
25 + 10z = 325
10z = 300
z = 30
y = 5 + z
y = 5 + 30
y = 35
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y = no. of $2 coins
z = no. of $5 coins
2007-10-30 18:09:37 補充：
我咪計左比你睇囉!!!
2007-10-30 18:10:08 補充：
y = 35 is the answer!!!
2007-10-29 7:04 am
Let x be the number of $2 coins.
Number of $1 coins = 3x
Number of $5 coins = x-5
3x + 2x + 5(x-5) = 325
5x+5x-25 = 325
10x = 300
x = 30
She has 30 $2 coins
Number of $1 coins = 3x
Number of $5 coins = x-5
3x + 2x + 5(x-5) = 325
5x+5x-25 = 325
10x = 300
x = 30
She has 30 $2 coins
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