Description: Sal is given the formula and a table of values that represent two people climbing a wall, and is asked to determine which one started out higher. Created by Sal Khan. Alyssa's height on the wall is given by the equation. a is equal to 1/3 t plus 5, where a is Alyssa's height in feet after climbing 4t seconds. Nick started racing at the same time as Alyssa and is also climbing at a constant speed.*Teacher Advisor is 100% free.