You buy 6 notebooks and a backpack. The cost of the backpack is $18.70. You pay 6% in sales tax on your purchase, and your total bill is $39.22. How much does each notebook cost?

$3.05

Step-by-step explanation:

Backpack=$18.70

6 note books=x

Sales tax=6%

Total cost=$39.22

18.70+x+0.06(18.70+x)=39.22

18.70+x+1.122+0.06x=39.22

19.822+1.06x=39.22

1.06x=39.22-19.822

1.06x=19.398

x=19.398/1.06

=18.3

x=$18.3

6 books=$18.3

Each book cost=18.3/6

=$3.05

step-by-step explanation:

de-gf

hj=3x+20

ji=15x-64

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.