What don't you understand. The objects goes straight up and then straight down.
Half the time it is going up and the other half of the time it is going down.
You must have been given an equation for these projectile type problems. What is this formula?
You know that the vertical distance from the ground, s(t), satisfies s(4.5) = 101.25 and s(9) =0.
You should know after 7 posts that we do not do problems for students.
Please post back showing your work.