Hmm... They were supposed to cover the necessary background material before they assigned this sort of exercise....

You are given that she used the equation , and that she converted this to an exponential model.

To learn how to convert between logarithmic and exponential equations, tryhere. Once you've learned about that, you'll see that her log equation would transform as:

. . . . .

To find the solution, you'll plug in the given value of "x".