0.95c
100% minus 5% is 95%, or 0.95. This means Sally only has to pay 0.95 times the grocery bill, or c, which represents 0.95c.
Since our line is perpendicular to this line, the slope of
our line is the negative reciprocal of 1/4, which is -4/1.
Remember, negative reciprocal is just a fancy way
of saying flip the fraction and change the sign.
So the slope of our line is -4/1 and we use this slope along
with our given point to write the equation of our line.
Start with the point-slope formula.
Y - y1 = m(x - x1).
~Substitute
Y - -2 = -4/1(x - 5).
Minus a negative is plus a positive.
Y + 2 = -4/1x + 20.
Subtract 2 from both sides.
Y = -4/1x + 18
So, our answer is C.
