From first equation of motion,
v = u + at
or v = 10 + 4 x 20
= 10 + 80 = 90m/s
Again from second equation of motion
s = ut + \(\frac{1}{2}\) at2
⇒ s = 10 x 20 + \(\frac{1}{2}\) x 4 x (20)2
⇒ 200 + \(\frac{1}{2}\) x 4 x 400
⇒ s = 200 + 800
= 1000 metres