Refer to the following mentioned data. 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 $12.95 billion. 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 2 decimal places