Forest rangers at a state park have observed a decline in the rate of trees per acre over a 5-year period. At the beginning of their observations, there was an
average of 48 trees per acre. At the end of the 5-year period, there was an
average of 42 trees per acre. If this trend continues, how many trees per acre
will there be 4½ years from the end of the 5-year observation period?