Particle A $($mA$=1$ kg$)$ is given initial velocity $10$ m$/$s to the right, while particle B $($mB$=1\mathrm{.}5$ kg$)$ is initially at rest. The coefficient of restitution for any impact between A and B is $2/3$ while the coefficient of restitution for impact of either particle with either wall is $0\mathrm{.}6.$ The particles slide along a smooth horizontal supporting surface.

Compute the percentage of the kinetic energy remaining in the system of A and B at the moment just before A impacts the wall on the left for the first time. $($Consider the system to have $100\%$ of its energy at the start.$)$ Neglect all friction.