Answer:
119.4% for 2017 and 100.0% for 2016.
Explanation:
                                                       2017                2016
Net sales                                 $276,200        $231,400
Cost of goods sold                  $151,900        $129,590
Operating expenses                $55,240         $53,240
Net earnings                             $27,820          $19,820
since we are using 2016 as a base year, the $231,400 in net sales represent 100%, so the trend percentage for 2017 = net sales 2017 / net sales 2016 $276,200 / $231,400 = 1.1936 = 119.4% or a 19.4% increase.
The base year's amount will always be 100% or 1, and the trend percentages will change relative to that year.