Help I have a time limit

Paper plates cost $8 per package and plastic utensils cost $5 per package. your supplier delivers 15 packages for a total cost of $90.

Cesar bought 7 items at the candy store. he bought candy bars for $0.50 each and packs of gum for $0.95 each. he spent a total of $6.80. what system represents the solution for the number of candy bars (x) and the number of pack gum (y) purchased?

How can you determine if a representation is a function or not ? answer this