Which of the following uses a variable to represent a person, place, or thing
that is unknown?
a. a c-sharp on the piano
b. apartment 12a
c. a b+ grade
d. mr. x

its 69.420

step-by-step explanation:

for this case we have by definition, if two lines are perpendicular, then the product of their slopes is -1.

then, given the following line:

so,

we are looking for m_ {2}:

then, the line is given by:

we find "b" replacing the given point:

finally, the equation is:

option c