Jackie is doing a marginal analysis to decide if she should spend any more money on a movie download. after figuring out her marginal cost and marginal benefit, she will

After Jackie figures out her marginal cost and marginal benefit, she will be able to figure out efficient quantity.  To achieve efficient quantity, marginal cost and marginal benefits should be equal. Meaning, what people are willing to give up should be equal to the value that would be given up.

Complementary goods. they go together, thats why one price increase and the others demand increases

Sjjdhdhdhd isk just trying to get points 12 r̰̃ṵ̃