For this case what you have to take into account is the following trigonometric definition:
Tan (x) = (C.O) / (C.A)
Where,
x: angle
C.O: opposite leg
C.A: Adjacent cateto.
We have then:
The tangent ratio is the ratio of the side opposite the angle of the side to the angle.
Answer:
opposite, adjacent

The slope is the difference of the y-coordinates divided by the difference of the x-coordinates, which gives us 5/2, or 2.5
The perpendicular line will have the x and y coefficients swapped and one of them negated. We can write the desired line as
9(x -6) -3(y -4) = 0
where the coordinates of the point of interest are (6, 4).
Dividing by 3, this is
3(x -6) -(y -4) = 0
3x -y = 14
An equation for the line of interest is ...
3x -y = 14
Normal price for 5 pages: number of pages times the price per page
(5)*($8.75) = $43.75
Discounted rate: $8.75 - $1.45 = $7.30
Discounted price for 5 pages:
(5)*($7.30) = $36.50