Answer:
[tex]s = ut + \frac{1}{2} at^{2} \\ ut = s - \frac{1}{2} a {t}^{2} \\ u = (s - \frac{1}{2} a {t}^{2} ) \div t \\ u = (s - \frac{1}{2} a {t}^{2} ) \times \frac{1}{t} \\ \\ u = \frac{s}{t} - \frac{1}{2t} a {t}^{2} \\ \\ u = \frac{s}{t} - \frac{1}{2} at \\ [/tex]
I hope I helped you^_^
