no need to worry about horizontal component here since the ball is launched directly upwards. You can see this:
u = 12.5
ux = 12.5cos(90) = 12.5 * 0 = 0
uy = 12.5sin(90) = 12.5 * 1 = 12.5
angle is 90 degrees above horizontal.
u = 12.5 ms^-1, after converting kmh^-1 to ms^-1 (just divide by 3.6)
Assume positive to be upwards, negative to be downwards.
(a)
Peak height is when the velocity is 0
v^2 = u^2 + 2gs (since its in the vertical component form)
-u^2 = 2gs
therefore s = - u^2/2g = 7.97 m
(b)
v = u + gt = 12.5 - 9.8(0.5)
= 7.6 ms^-1
(c)
v = u + gt = 12.5 - 9.8(1.5)
= -2.2 ms^-1