That is system of equation.
For this case we have that by definition, the slope of a line is given by:

Two points are needed through which the line passes:

Substituting:
Rounding:

Answer:

I have no clue what this answer is but I hope you find it out
Answer:
1 kilometre is 0.621 mile
Answer is C).
One way to find the answer is to multiply the $54 by .30 (which is 30%converted to a decimal). Doing this will give you what 30% of $54 is.
This gives you 16.2
Since the question is asking what 30% off the price is, subtract the 16.2 from the $54.