Equation rearrangement

Previously (in the Throwing & free falling skill) we arrived at these two equations for our flying orange-cannon shot orange:

$\displaystyle s_y=v_{y,0}t- \frac12 gt^2\qquad$ and $\qquad {s_x}=v_{x,0}t$

Its technical sheet tells a muzzle velocity of $5\,\mathrm{m/s}$. At your shooting angle this could mean $4\,\mathrm{m/s}$ vertically and $3\,\mathrm{m/s}$ horizontally. So, we know the values $v_{x,0}=3\,\mathrm{m/s}$ and $v_{y,0}=4\,\mathrm{m/s}$.¹ They are not unknowns anymore. In the two equations there are thus only three unknowns left: $s_x$, $s_y$ and $t$.²