A hiker is 3.5 miles from her campsite when she begins to walk back to it. She hikes back toward the campsite at a constant rate of 2.1 miles per hour. Which equation models the distance of the hiker from her campsite? (Let m represent her distance, in miles from the campsite and h represent the number of hours since she begin walking back.)
O m= 3.5+ 2.1h
Om= 3.5h - 2.1
O m = 3.5h + 2.1
m = 3.5 - 2.1h