i throw a banana vertically up into the air at an intial speed of 10m/s it accelerates down at 10m/s/s calculate the maximum height of the banana?

I know you have to use suvat equations In this question but I don't understand how you get enough values in order to do this?
Any help would be much appreciated

F = m a

weight = m a

a = -mg/m = - g
in other words acceleration is down at -10 m/s^2

dv/dt = a = -10
so
v = -10 t + c
but at t = 0, v = +10
so
c = 10
and
v = -10 t + 10
now at the top, v = 0
0 = -10 t + 10
so at the top when t = 1

if v = -10 t + 10
then
h = Hi + 10 t - 5 t^2
initial height Hi = 0
so what is h when t = 1?
h = 10(1) -5 (1)^2
h = 5 meters