On a website selling books, three paperback books and five hardcover books cost $80.10, and seven paperback books and four hardcover books cost $100.65. what is the total cost of one paperback and one hardcover book?

Let us represent

Paperback books = p

Hardcover books = h

Three paperback books and five hardcover books cost $80.10

3p + 5h = 80.10Equation 1

Seven paperback books and four hardcover books cost $100.65

7p + 4h = 100.65Equation 2

Step 1

We have to find the cost of each paperback and hardcover book. We do this using the Elimination Method.

3p + 5h = 80.10Equation 1

7p + 4h = 100.65Equation 2

Multiply Equation 1 by 4 and Equation 2 by 5 to eliminate h

12p + 20h = 320.4Equation 3

35p + 20h = 503.25Equation 4

We subtract Equation 3 from Equation 4

23p = 182.85

We divide both sides by 23

23p/23 = 182.85/23

p = 7.95

The cost of one paperback book is $7.95

We solve for h, the cost of one hardback book by substituting 7.95 in Equation 1

3p + 5h = 80.10Equation 1

3(7.95) + 5h = 80.10

23.85 + 5h = 80.10

5h = 80.10 - 23.85

5h = 56.25

We divide both sides by 5

5h/5 = 56.25/5

h = 11.25

The cost of one hardback book is $11.25

Step 2

The cost of one paperback book is $7.95

The cost of one hardback book is $11.25

The total cost of one paperback and one hardcover book is

$7.95 + $11.25 = $19.20

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introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.

no solution

step-by-step explanation:

there is not enough information in the problem to solve.