Required: a. Calculate the gross profit ratio for each of the past three years. b. Assume that Campbell's net sales for the first four months of 2021 totaled $3.2 blllion. Calculate an estimated cost of goods sold and gross profit for the four months, using the gross profit ratio for 2020. Complete this question by entering your answers in the tabs below. Calculate the gross profit ratio for each of the past three years. Note: Round your answers to 1 decimal place