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Each writer of the local newspaper is paid as follows: a

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Intern
Joined: 07 Mar 2013
Posts: 6
Each writer of the local newspaper is paid as follows: a  [#permalink]

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15 Mar 2013, 23:17
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35% (medium)

Question Stats:

72% (02:09) correct 28% (02:10) wrong based on 124 sessions

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Each writer of the local newspaper is paid as follows: a dollars for each of the first n stories each month, and a + b for each story thereafter, where a > b. How many more dollars will a writer who submits n + a stories in a month earn than a writer who submits n + b stories?

A. (a + b)(a + b + n)
B. a - b
C. a^2 - b^2
D. n(a - b)
E. an + bn - an

Lets assume a=$10, b=$5, n=5 stories

For (n+a)=15 stories, the dollars earned is $10+10*$15=$160 For (n+b)=10 stories, the dollars earned is$10+5*$15=$85
Difference = $160 -$85 = $75 Now, input these variable values in the answer choices & observe only C equals$75.

my question is how it is right to add the number of stories with the money? as shown in the explanation
(n+a)=15 stories, and
(n+b)=10 stories
stories and money are two different things
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Re: Each writer of the local newspaper is paid as follows:  [#permalink]

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16 Mar 2013, 00:14
1
You can add the number of stories with the money, a,b and n represent numbers; the fact that they are "stories" or "money", it' s not relevant.

However the formula is:
$$a*n + (TS - n)(a + b)$$

TS= total stories

The difference is:
$$[an + (n+a-n)(a+b)] - [an +(n+b-n)(a+b)]$$

$$[an + a(a+b)] - [an + b(a+b)]$$

$$a(a+b) - b(a+b)$$

$$a^2+ab-b^2-ab$$

$$a^2-b^2$$
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Joined: 07 Mar 2013
Posts: 6
Re: Each writer of the local newspaper is paid as follows:  [#permalink]

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16 Mar 2013, 00:34
Zarrolou wrote:
You can add the number of stories with the money, a,b and n represent numbers; the fact that they are "stories" or "money", it' s not relevant.

However the formula is:
$$a*n + (TS - n)(a + b)$$

TS= total stories

The difference is:
$$[an + (n+a-n)(a+b)] - [an +(n+b-n)(a+b)]$$

$$[an + a(a+b)] - [an + b(a+b)]$$

$$a(a+b) - b(a+b)$$

$$a^2+ab-b^2-ab$$

$$a^2-b^2$$

it's not question, but thank you anyway
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Joined: 16 Oct 2010
Posts: 9326
Location: Pune, India
Each writer of the local newspaper is paid as follows: a  [#permalink]

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09 Jan 2019, 08:14
Quote:
my question is how it is right to add the number of stories with the money? as shown in the explanation
(n+a)=15 stories, and
(n+b)=10 stories
stories and money are two different things

Note that number of stories is just a number say n = 2 and money is just a number too say a = 5.
So if you have 7 of something (say 7 stories), you can show it as (n + a) = (2 + 5) = 7
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Each writer of the local newspaper is paid as follows: a   [#permalink] 09 Jan 2019, 08:14
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