i don't think we can find time in this case...you can use a bit of maths to solve for the original velocity though...
\fn_cs \120dpi \Delta _x = U_x t
\fn_cs \120dpi since \ we \ don't \ know \ time, t=\frac{V_0-u_y}{a}
\fn_cs \120dpi Also \ at \ the \ end \ of \ the \ parabolic \ motion \...