1/4 off means 0.25 * 28
7
Sale price = 28-7
= 21
The slope of a line perpendicular to another line has a
slope which is the negative reciprocal of that line or:
m1 = -1/m2
First, we convert the given equation into slope-intercept
form of a line: y = mx + b
8x + 15y = 12
15y = -8x + 12
y = (-8/15) x + 0.8
m1 = -8 / 15
Therefore the slope of the perpendicular line is:
m2 = 15 / 8
Since the perpendicular line crosses the point (11, 17), therefore
using the slope formula:
m = (y2 – y1) / (x2 – x1)
15 / 8 = (y2 – 17) / (x2 – 11)
1.875 (x2 – 11) = y2 – 17
1.875 x2 – 20.625 = y2 – 17
y2 = 1.875 x2 – 3.625
y = (15/8) x – 3.625
multiplying both sides by 8:
8y = 15x – 29
rewriting in standard form:
<span>15x – 8y = 29 (ANSWER)</span>
