Answer:
A) Canned and Packet
Grain, Meat and Vegetables
B) Let C = canned goods, let P = packet goods
20C + 7P
Let G = grain, let M = meat, let V = vegetables
7G + 3M + 17V
C) The number of grain and packet goods are the same in each expression, as this food group has been packaged in the same way.
The other variables in both expression are different. The meat and vegetable food groups have been separated in the second expression, whereas they are part of the same group in the first expression.