You work at a beauty supply store and need to order 50 cases of hairspray. One company sells the hairspray for $7.95 per case, plus 8% sales tax. A second company sells the hairspray for $11.95 per case. The second company also offers a rebate of 20% for the whole order, but charges no additional sales tax. If you choose the better of the two prices, how much will you pay for the 50 cases of hairspray? $200.00
$397.50
$429.30
$478.00
$597.50

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.

it is a horizontal line.

well, because the $0.25 is an added cost depending on how many minutes, the answer would be y = 30 + 0.25x.