Tara throws a party every month. The number of cupcakes Tara bakes depends on how many kids will be at the party. Tara likes to have two cupcakes per kid. Let c be a variable representing the number of cupcakes Tara bakes, and let k be a variable representing the number of kids who will be at the party. You can also let l represent Tara's sense of inner loneliness, but that one won't play a part in this particular equation: c = 2 · k.Which variables vary in this situation?