20 markers are needed to cover the 10 kilometers.
What are you looking for?
You can use the properties of logarithm to get to the solution.
The approximate value for given term is given by

<h3>What is logarithm and some of its useful properties?</h3>
When you raise a number with an exponent, there comes a result.
Lets say you get

Then, you can write 'b' in terms of 'a' and 'c' using logarithm as follows

Some properties of logarithm are:

<h3>Using the above properties</h3>

Thus,
The approximate value for given term is given by

Learn more about logarithm here:
brainly.com/question/20835449
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