Like bought 15 boos six books each cost $7 four of the books each cost $5 the rest of the books each cost $3 how many do all the books cost in all

The total combined cost of 15 books  is $77.

Step-by-step explanation:

Here, the total number of books purchased  = 15

The cost of books = $7 for 6 books

So, the cost of six books  =  6 x ( cost of 1 book) = 6 x ($7)  = $42

⇒Out of 15 books, the cost of 6 books  = $42   (1)

The cost of books = $5 for 4 books

So, the cost offour books  =  4 x ( cost of 1 book) = 4 x ($5)  = $20

⇒Out of 15 books, the cost of 4 books  = $20   (2)

Now, the left books are at cost $3 each book.

The number of left books  = 15 - ( 6+4) = 15 - 10 =  5

So, the cost of books = $3 for 5 books

So, the cost of five books  =  5 x ( cost of 1 book) = 5 x ($3)  = $15

⇒Out of 15 books, the cost of 5 books  = $15   (3)

Now, to get the total price of 15 books add (1) + (2) + (3), we get:

$42 + $20 + $15  = $77

Hence, the total combined cost of 15 books  is $77.

the above table 1 will calculate the population size (n) after a certain length of time (t). all you need to do is plug in the initial population number (no), the growth rate (r) and the length of time (t). the constant (e) is already entered into the equation. it stands for the base of the natural logarithms (approximately 2.71828). growth rate (r) and time (t) must be expressed in the same unit of time, such as years, days, hours or minutes. for humans, population growth rate is based on one year. if a population of people grew from 1000 to 1040 in one year, then the percent increase or annual growth rate is 40/1000 x 100 = 4 percent.

step-by-step explanation: