5, 10, 15, 20. i think that's what it means.get a second opinion.
Answer:
C. Slope and 
Step-by-step explanation:
We're missing the graph itself, but I can make an educated guess:
- Assuming x = volume and y = mass:

density = mass/volume
x = volume = run
y = mass = rise
mass/volume = rise/run = slope
The slope of the line (assuming the graph is purely linear) represents mass/volume, which is the formula for density.
I had to Google the density of silver itself. Do the math from the graph for a more appropriate answer, as the graph may be less scientifically precise.
58 plus tip of .20
so
58 times 0.2 = 11.6 is the tip
now we add tax (Presuming we son't tax the tip)
58 times 0.07 = 4.06 the tax
so its
58 + 11.6 + 4.06 = $73.66 total cost
You have to round it to the nearest hundreds