Given
Initial speed, u=45 m/s
Acceleration
[tex]a=-\frac{8m}{s^2}[/tex]Time taken, t=4 sec
To find
The final speed
Explanation
Let the speed he be going in be v
Thus,
[tex]\begin{gathered} a=\frac{v-u}{t} \\ \Rightarrow-8=\frac{v-45}{4} \\ \Rightarrow-32+45=v \\ \Rightarrow v=13\text{ m/s} \end{gathered}[/tex]Conclusion
The velocity he is going in is 13 m/s.
