Bir kırtasiyeci aldığı kalemlerin tanesini 2 liradan satarsa 40 lira kâr, 1,5 liradan satarsa 20 lira zarar ediyor. Bu kırtas

Question

Bir kırtasiyeci aldığı kalemlerin tanesini
2 liradan satarsa 40 lira kâr, 1,5 liradan
satarsa 20 lira zarar ediyor.
Bu kırtasiyeci kaç kalem alıp satmış-
tır?
A) 125 B) 120 C) 115 D) 110​

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Sapo 5 years 2021-07-17T16:43:10+00:00 1 Answers 18 views 0

Answers ( )

  1. thachthao
    0
    2021-07-17T16:44:26+00:00
    Reply

    Answer: Option B: 120.

    Step-by-step explanation:

    I will answer in English

    This problem can be translated to:

    A man bought N pens, (at a cost C) if he sells each pen at 2 lira, he will have a profit of 40 lira.

    If he sells each pen at 1.5 lira, he will loss a total of 20 lira.

    We want to find N, the number of pens that he bought.

    if he sells the N pens at 2 lira each, the revenue is:

    N*2 lira

    And the profit is the difference between the revenue and the cost, then the profit (40 lira in this case) is:

    N*2 lira – C = 40 lira.

    When he sells each pen at 1.5 lira the equation is:

    N*(1.5 lira) – C = -20 lira.

    Then we have two equations:

    N*2 lira – C = 40 lira.

    N*(1.5 lira) – C = -20 lira.

    To solve this we need to isolate the variable C in one of the equations, i will isolate C in the second equation:

    N*(1.5 lira) + 20 lira = C.

    Now we can replace this in the first equation to get:

    N*(2 lira) – (N*(1.5 lira) + 20 lira) = 40 lira.

    We can solve this for N.

    N*(2 lira) – N*(1.5 lira) – 20 lira = 40 lira

    N*(2 lira – 1.5 lira) = 60 lira

    N*(0.5 lira) = 60 lira

    N = (60lira/0.5lira) = 120

    N = 120

    This means that he bought 120 pens.

    The correct option is B.

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Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )