To change from meters per day into kilometers per year, you just have to change from meters to kilometers and from days to years. You just multiply/divide by the unit conversions (for example, 1000 meters per kilometer) in a way that cancels out the units and leaves just kilometers and years:
[tex](\frac{20\ meters}{day})(\frac{1\ kilometer}{1000\ meters})(\frac{365\ days}{year})=7.3\ kilometers\ per\ year[/tex]
The meters on the top of the first section cancels out with the meters on the bottom of the second section, and the days on the bottom of the first section cancels out with the days on the top of the last section, leaving just kilometers and years. The answer is 7.3 kilometers per year.
