### Home > CCA2 > Chapter 6 > Lesson 6.1.1 > Problem6-15

6-15.

The cost of food has been increasing by 4% per year for many years. To find the cost of an item 15 years ago, Heather said, “Take the current price and divide it by $(1.04)^{15}$.”

Her friend Elissa said, “No, you should take the current price and multiply it by $(0.96)^{15}$ !

Explain who is correct and why. Homework Help ✎

Since the situation describes an increase, the multiplier must be 1.04. In this situation, x will represent cost.
What will x be 15 years in the past?

Heather is correct, because a 4% decrease does not ''undo'' a 4% increase.