Hi
Yes 15 kilometers is 1500000 cm
This is because in metric conversion, you multiply by ten each time you convert to the next unit.
Heres a useful way to remember
K ing (kilo)
H enry (hecto)
D oesn't (deca)
U sually (unit) <-metre, litre ect.
D rink ( deci)
C hocolate (centi)
M ilk (milli)
The answer to that would be 0 because the line goes through the orgin witch the points are 0
I think it is the second one, zero slope :)