A soccer ball has a mass of $0\mathrm{.}42$ kg when it is kicked from rest by a foot that has a mass of $5\mathrm{.}9$ kg$.$ The coefficient of restitution between the ball and the foot is $0\mathrm{.}72$ and the final velocity of the ball just as it leaves the foot during the shot is $24\mathrm{.}9$ m$/$s$.$

a$)$ What is the velocity of the foot in meters per second $($m$/$s$)$ just as it makes contact with the ball during the shot?