Keep Moving !!!!!

The potential energy of a particle of mass $5kg$ moving in the $XY~plane$ is given by $U=(-7x+2y)J$ where $x$ and $y$ are given in $metres(m)$ . If the particle starts from rest from the origin , then what is the velocity of the particle at time $t=2s$ ?????

Note : Give your answer in $m/s$ and avoid the units.....just write the answer as an integer !!!!!