there are some $5 coins and $2 coins in a saving box and the number of $5 coins is 6 more than that of the $2 coins.If the value of the coins is $128, find the total number of coins in the box.
please show step and use algebra..
Thank you..
F.1 Maths
2007-04-13 10:23 pm
回答 (3)
2007-04-13 10:57 pm
✔ 最佳答案
x = number of $5 's coiny = number of $2 's coin
5x + 2y = 128 --------------------------------------------------- ( 1 )
x - y = 6 --------------------------------------------------- ( 2 )
from ( 2 )
x = 6 + y -------------------------------------------------- ( 3 )
substitute ( 3 ) into ( 1 )
5 ( 6 + y ) + 2 y = 128
30 + 5 y + 2 y = 128
7 y =128 - 30
y = 98 / 7
y=14 -------------------------- ( 4 )
substitute ( 4 ) into ( 3 )
x = 6 + y
x = 6 + 14
x = 20
total coins = x + y
= 20 + 14
= 34 coins
參考: me (^_^)
2007-04-13 10:31 pm
Let no of $2 coin is X
no of $5 coin is 6X
2X+(6X)*5=128
2X+30X=128
X=4
Total
$2 coin = 4 =$8
$5 coin = 6*4= 24 = $120
no of $5 coin is 6X
2X+(6X)*5=128
2X+30X=128
X=4
Total
$2 coin = 4 =$8
$5 coin = 6*4= 24 = $120
2007-04-13 10:31 pm
Let x be the no. of $5 coins
y be the no. of $2 coins
x=y+6
5x+2y=128
5(y+6)+2y=128
7y+30=128
7y=98
y=14
x=y+6
x=14+6
x=20
Therefore, there have 20+14=34coins in the box
y be the no. of $2 coins
x=y+6
5x+2y=128
5(y+6)+2y=128
7y+30=128
7y=98
y=14
x=y+6
x=14+6
x=20
Therefore, there have 20+14=34coins in the box
收錄日期: 2021-04-13 00:33:25
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070413000051KK02614