The slope of the parallel line is -6/7
the slope of the perpendicular line is 7/6
the slope of the line = -6/7
the gradient of two parallel lines are equal
the product of the gradient of two perpendicular lines is -1
: the gradient m1*m2 = -1
m2= -1(-6/7)
m2= 7/6
The student will have $135 in her bank account at the end of the ninth week. You can fine this out by finding out the amount she deposits a week and to do this you would take the $30 and divide it by 2 because she had $30 at the end of the second week.
30/2=15
So you see that the student deposits $15 each week, so to find out how much money she will have in 9 weeks you will multiply her $15 by 9.
15x9=135
So the student will have $135 at the end of the ninth week.
We are given an equation:

This is an equation of a circle. General form of a circle equation is:

Where:
a = x coordinate of a center
b = y coordinate of a center
r = radius of a circle
Motion detector can detect person anywhere within a boundary. The greatest distance at which detector can detect is at the edge of a circle. That distance, between detector and edge of circle, is equal to radius.
From the equation we have:

The greatest distance at which person can be detected is 4ft.
7 1/3
I think this is it, i would like for u to get a second opinion.