Answer :
[tex]v=v_0-32t[/tex]
we can replace the velocity (24ft/s) and the time(3s)
[tex](24)=v_0-32(3)[/tex]simplify
[tex]24=v_0-96[/tex]and solve for v0
[tex]\begin{gathered} 24+96=v_0 \\ \\ v_0=120 \end{gathered}[/tex]then the initial velocity is 120 feet per second