The expression is given as,

Substitute the value t=3 in the above expression and obtain the velocity corresponding to 3 seconds,

Thus, the velocity of the skydiver is 29 m/s after 3 seconds.
Substitute the value t=5 in the above expression and obtain the velocity corresponding to 5 seconds,

Thus, the velocity of the skydiver is 39 m/s approximately after 5 seconds.