A) From the table, value A is in the intersection between 'Like chocolate cake' and 'Like cheesecake'; therefore A is the number of people who like both chocolate cake and cheesecake.
Similarly, in the case of B, C,..., I
B) From part B, value E corresponds to the number of people who do not like either chocolate cake or cheesecake.
Thus, the answer to part B) is
Notice that E/I alone is a decimal number.
C) We cannot know without the explicit values of the constants. Value E could be equal to 0 or close to I.