13. Each year, a school manages to use only 90% as much paper as the previous year. In the year 2010,
they used 700 000 sheets of paper.
a. Find out how much paper the school used in the years 2011 and 2012
b. Find an explicit equation to calculate how much paper they used in 2021
C. How much paper did they use in total from 2010 to 2021?