motion in staright line-part-3 ,sign conventions questions neet ,jee main

A ball is thrown vertically upwards with a velocity of 20m/s from the top of a multi storey building.The height of the point from where the ball is thrown is 25m from the ground.
(a)How high will the ball rise
(b)How long will it be before the ball hits the ground.
Take g=10m/s