Hi I am having trouble with the following question. Any help would be highly appreciated!

My attempt was using the equation d=v1*t + 0.5*a*t^2 where a = 9.8m/s^2 because the box fell out of the car. So i had to solve a quadratic and I got t about 111s. Is that right?A box accidentally falls from the back of a truck and hits the ground with a speed of 15.0m/s. It slides along the ground for a distance of 45m before coming to rest.

a) find the length of time the box slides before stopping

Thank you for your time!