Hi!
You didn't list the options, but I think I know the answer. Let me know if my answer isn't listed! :)
We need to multiply the exponents.3 · -5 = -15
The answer is 
Hope this helps! :)
You haven't provided the graph, therefore, I cannot provide you with a specific solution for this question.
However, I will tell you how to solve it and you can apply on the graph you have.
Now, we are given that:
x-axis represents the distance in ft
y-axis represents the time in minutes
To get the time that she has walked when she reaches the farthest point from her house, all you have to do is:
1- go to the greatest point on the x-axis. This point would be representing the farthest distance.
2- get the value of the y corresponding to the x-point you got in step one. This would be the time walked when she reaches the farthest point which is the value you are looking for.
Hope this helps :)
The new slope would now be 2 so y=2x-3