Please help me to solve this problem.

Question

A body is projected vertically upwards with a velocity 20m/s. find the maximum height reached by the body.(g=10m/sec2)

Answer 1

v = Vi + a t
we want the top where v = 0
Vi = +20
a = -10
so
0 = 20 - 10 t
t = 2 seconds to top
h = Vi t + (1/2) a t^2
h = 20 (2) - (1/2)(10) (2)^2
h = 40 - 20
h = 20

Answer 2

20M