P 5-4 Computations (upstream and downstream sales)

Comparative income statements of Son Corporation for the calendar years 2016, 2017, and 2018 are as follows (in thousands):

2016 2017 2018 Sales $48,000 $51,000 $57,000 Cost of sales 25,200 26,400 30,000 Gross profit 22,800 24,600 27,000 Operating expenses 18,000 19,200 22,800 Net income $ 4,800 $ 5,400 $ 4,200 ADDITIONAL INFORMATION