Remember that the axis of symmetry (a vertical line that passes through the vertex) is exactly halfway between the two x-intercepts. Thus, the x-coordinate of the vertex is 7.
If you really want to figure this out you make an equation to solve for the time let's let x = time from Elena to Jada and x = time from Jada to Elena 12 then the equation 12 = 5x +3x would help figuring out their distance say for one of them 12 = x(5+3) 12/8 = x 1.5 = x 1. 5 hours they will meet up