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Studentka2010 [4]
3 years ago
15

There are 420 books on a bookcase with 7 shelves. Each shelf has the same number of books. How many books are on 4 shelves? 28 6

0 120 240 ...
Mathematics
1 answer:
Ghella [55]3 years ago
3 0
If we have 420 books for every 7 shelves and are looking for how many books are on 4 shelves, we need to set up fractional proportions.

We have 7 shelves for every 420 books, so we will have our first fraction like this:
7/420.
We also have 4 shelves for every x books, so our second fraction will be 4/x.

Set these fractions up as an equation.
7/420 = 4/x

To solve for x, we need to cross multiply the numerators of one fraction with the denominators of the other fraction.
In other words, multiply the top number of one fraction by the bottom number of the other question.

It should look like this:
7(x)
420(4)

7(x) = 7x
420(4) = 1680

Set your products up as an equation.
7x = 1680

Now to solve for x, we need to simplify.
Currently, x is being multiplied by 7.
To get x alone, divide 7x by 7.
Remember, what you do to one side of an equation, you must do to the other, so divide 1680 by 7.

7x / 7 = x
1680 / 7 = 240

You are left with:
x = 240.

For every 4 shelves you have 240 books.

I hope this helps!

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Hi there! So 39,300 copies of a book were sold on debut month of release, and that represents 6.3% of all copies sold to date. To find the total amount of copies sold, we can write and solve a proportion. Set it up like this:

39,300/x = 6.3/100

We set it up like this because 39,300 is part of the total amount, and it represents 6.3% of the total book sales. Percents are parts of 100, which is why 6.3 is above 100. Let's cross multiply the values. 39,300 * 100 is 3,930,000. 6.3 * x is 6.3x. that makes 3,930,000 = 6.3x. Divide each side by 6.3 to isolate the x. 6.3x/6.3 cancels out. 3,930,000/6.3 is 623,809.5238 or 623,810 when rounded to the nearest whole number. There. The total amount of copies sold to date is about 623,810.
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A number increased by nine (n + 9) is the same as nine increased by a number (9 + n), the correct option is C.

<h3>What is the pharse in mathematics?</h3>

A mathematical phrase is a set of words or a combination of words and numbers that can be written as a mathematical expression.

Given

Jillian was asked to translate the expression 9 + n into words.

She wrote "a number increased by nine.

The expresion can be written into the two formate which is;

(n+9) and (9+n)

Hence, a number increased by nine (n + 9) is the same as nine increased by a number (9 + n), the correct option is C.

To know more baout pharse click the link given below.

brainly.com/question/22314482

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Step-by-step explanation:

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