Vivan has brought along an altimeter to measue her evelation at different places in the valley. vivian first ride was the ferris wheel. when she sat on the wheel at its lowest point her altimmeter read -9.6 feet. when she reached the top of the wheel her altimeter read 12.3 feet.

Is the change in vivians elevation from the bottom of the ferris wheel to the top a positive number of a negeative