Libby is hiking with her family on Saturday morning. They want to get to the picnic shelter, located at 86.9 feet above sea level, by lunch time. They need to increase their elevation by 35.8 feet to get there. If f = their family's current elevation, write an equation that shows their total increase in elevation during the morning hike. Your equation should represent the situation. The variable should not be alone/isolated on one side of the equation. Set up the problem.