There are 17 appetizers available at a restaurant. from these, barbara is to choose 12 for her party. how many groups of 12 appetizers are possible?

This is a question of combination. In other words, the question requires determination of number of ways in which 12 appetizers can be chosen form a total of 17 appetizers.

Therefore,
Possible number of 12 groups = 17C12 = 17!/[12!*(17-12)!] = 6188

1.17+3.99a. you combine the terms with a to create 3.99 and the 1.17 stays because it has no like terms or a variable