Anonymous
Anonymous asked in 科學及數學數學 · 6 years ago

# 數學唔識,幫幫手,有廿點架,急

1. 6 books and 8 magazines cost \$148;11 books and 7magazines cost \$233,find the cost of a book and that of a magazine.

2.the customer of an internet company has to pay a fixed cost plus an extra amount calculated according to the web-surfing time.if a customer spends 35 hours for web-surfing,the payment is \$173.If he spends 48 hours for web-surfing,the payment is \$202 find the fixed cost and the amount for web-surfing per hour.

Update:

### 3 Answers

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• 6 years ago
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1. 6 books and 8 magazines cost \$148;11 books and 7magazines cost \$233,find the cost of a book and that of a magazine.

2013-08-26 19:08:42 補充：

Let x be the cost of a book and y be the cost of a magazine.

6x+8y=148

11x+7y=233

by solving, x=18 y=5

the cost of a book and that of a magazine is \$18 and \$5 respectively.

2013-08-26 19:12:38 補充：

2.

Let x be the fixed cost and y be amount for web-surfing per hour

x+35y=173

x+48y=202

by solving, x=94.9 y=2.23( cor.to 3 sig. fig.)

Thus, the fixed cost and the amount for web-surfing per hour is \$94.9 and \$2.23 respectively.

• Anonymous
6 years ago

好的><謝謝你的意見啊><和教法,看完你的做法,有點明了

2013-08-26 23:14:42 補充：

現在全明了!!感激感激T^T

• 6 years ago

芷晴，你要學：

6x+8y=148　．．．（１）

11x+7y=233　．．．（２）

（１）乘１１：66x+88y = 1628　．．．（３）

（２）乘　６：66x+42y = 1398　．．．（４）

（３）－（４）：46y = 230　＝＞　y = 5

Put into （１）： 6x+8(5)=148　＝＞　x = 18

明白嗎？

這類計法必須掌握妥當。

第二題較簡單，試自己做。

2013-08-26 23:55:56 補充：

努力加油！！！！！！！！！！

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