We know the x axis is in days and the y axis is the distance in miles. There are only three answers left. We can also cross out 50 miles per day since the rate of change is less then 50. The answer is 35 miles per day because if the rate of change were to be 25 in 4 days the distance would be 100 miles, while is you look at where the point is at it is closer to 150.
This is because if she got the bag for 50% off, 30 divided by 2 is 15$, 45 divided by 2 is 22.5, 60 divided by 2 is 30$ so option C. Would be your answer.
