Answer:
y = -0.2x - 5.8
Step-by-step explanation:
If a line is given in the form y = mx + b, the "m" is the slope.
For the line given y = 5x, the slope is 5
The line that is perpendicular to this will have slope that is "negative reciprocal of that".
So, the perpendicular line will have slope of 
So, the Perpendicular Line will have equation:
y = -1/5x + b
Let's find b by replacing x with 6 and y with -7 [the point given]. So we have:

So the equation of perpendicular line = y = -0.2x - 5.8
Vertex=(-1,0)
x^2-2x-1
y=− ( x + 1 )^2 + 0
Use the vertex form, y=a(x−h)^2+k, to determine the values of a, h, and k.
Find the vertex (h,k) = (-1,0)
Assuming you are trying to get price per pound.
Divide 750 by 5 which equal 150 or $1.50
In math and and other types of school stuff :) if that's what your asked