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:

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3 Answers

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  • 6 years ago
    Favorite Answer

    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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