Why is the slope unidentified for vertical lines

see below

Step-by-step explanation:

Vertical lines have the same x coordinates

The slope is given by

m = (y2-y1)/(x2-x1)

The x values are the same

m = (y2-y1)/(x-x)

m = (y2-y1)/ 0

Any number, except 0, divided by 0 is undefined

40% off the regular price is the correct answer.

step-by-step explanation:

x > 1.3

step by step:

8.5−0.9x> 9.8−1.9x

step 1: simplify both sides of the inequality.

−0.9x+8.5> −1.9x+9.8

step 2: add 1.9x to both sides.

−0.9x+8.5+1.9x> −1.9x+9.8+1.9x

1x+8.5> 9.8

step 3: subtract 8.5 from both sides.

1x+8.5−8.5> 9.8−8.5

1x> 1.3

step 4: divide both sides by 1.

1x/1 > 1.3/1