8 books cost 11.20. Find the cost of 5 books

First of all we have to find the cost of a book then multiply it by 5 :

$ 11.20 ÷ 8 = $ 1.4

$ 1.4 × 5 = $ 7

Thus 5 books have a cost of $ 7 .

The cost of 5 books is $7

Step-by-step explanation:

If there are 8 books and you need to find the cost of 5, you need to first find the cost for one book.

If 8 books cost 11.20.

11.20 ÷ 8 = 1.40

1.40 is the cost of one book

1.40 x 5 = 7

So the cost of 5 books is $7

I tried my best to explain

the largest number of the four options is 1.8 x 10-2

you have it in scientific notation.

1.80 x 10-6   = 0.00000180

1.80 x 10-4   = 0.000180 (bigger, or "less small", than the former one)

so

1.8 x 10-2       = 0.0180. as you see. the "less small", or the biggest one of them all.

as you have negative exponent, it means you are dividing 1.8 by 100 (i.e. moving the dot towards left, two times).

if you had positive exponent for the scientific notation, power of tenths, you would be multiplying times 100 (moving the dot towards right) as below:

1.8 x (10)2 = 180

so. if you have negative exponent in scientific notation, move the dot toward left. if it is positive, toward right as many times the exponent tells you.

n=9

step-by-step explanation:

7 times a number = 7n

decreased by 13 = 7n-13

same as is =

5 times the number = 5n

increased by 5 = 5n+5

7n-13 = 5n+5

2n=18

n=9