Find tye equation of the line shown

Which property is illustrated by the statement given below? raj raj.

The appalachian trail is a hiking trail that passes through the appalachian mountains. three members of a teen hiking group hiked a section of the trail. the hikers stopped at a rest area and equally shared 3 4 gallon of water. how much water did each person get?

How do you use the elimination method for this question? explain, because i really want to understand!