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Anton [14]
3 years ago
11

The bookstore ordered 15 Sociology work books and 10 Economy 101 textbooks on August 1st to prepare for the fall semester. After

realizing they miscounted, the bookstore order 1 more Sociology workbook and three more Economy 101 textbooks on August 15th. If August 1st the order was for $4300 and the August 15th order was $800 , find the cost of one Sociology workbook and one Economy 101 textbook?
Mathematics
1 answer:
vaieri [72.5K]3 years ago
8 0
E = number of books on Economy
s = number of books on Sociology

so the order on August 1st looks like 15s + 10e = 4300
and the order on August 15th looks like 1s + 3e = 800

\bf \begin{array}{lllll}
15s&+&10e&=&4300\\
s&+&3e&=&800
\end{array}\\\\
-------------------------------\\\\
\boxed{s}=800-3e\qquad thus
\\\\\\
15s+10e=4300\implies 15\left( \boxed{800-3e} \right)+10e=4300\qquad then
\\\\\\
12000-45e+10e=4300\implies 12000-4300=45e-10e
\\\\\\
7700=35e\implies \cfrac{7700}{35}=e\implies \boxed{220=e}
\\\\\\
now \qquad s+3e=800\implies s+3(220)=800\implies s=800-660
\\\\\\
\boxed{s=140}
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Answer:

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Step-by-step explanation:

Cost per item is found by dividing the cost by the number of items. If the woman bought n items for $120, the cost of each item is $120/n. If the woman bought 24 more items, n+24, at the same price, then the cost per item is $120/(n+24). The problem statement tells us this last cost is $16 less than the first cost:

120/(n+24) = (120/n) -16

Multiplying by n(n+24) gives ...

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The woman bought 6 items.

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When the woman bought 6 items for $120, she paid $120/6 = $20 for each of them. If she bought 6+24 = 30 items for the same money, she would pay $120/30 = $4 for each item. That amount, $4, is $16 less than the $20 she paid for each item.

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4 years ago
Monica’s school band held a car wash to raise money for a trip to a parade in New York City. After washing 125 cars, they made $
nikklg [1K]

The system of linear equations represents the situation is;

x + y = 125

x + y = 1255x + 8y = 775

<h3>Simultaneous equation</h3>

Simultaneous equation is an equation in two unknown values are being solved for at the same time.

let

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From equation (1)

x = 125 - y

5x + 8y = 775

5(125 - y) + 8y = 775

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- 5y + 8y = 775 - 625

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y = 150/3

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x + 50 = 125

x = 125 - 50

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Therefore, the number of quick washes and premium washes Monica’s school band had is 75 and 50 respectively.

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