Problem $4$ According to

Edmunds.com, the $2011$ Toyota Prius has a mass of $3042lbm.$ If a Prius is traveling at $40mph,$ what is its kinetic energy, in kJ$?$ Assume that the Prius is brought to a stop and $60\%$ of its kinetic energy is recovered and deposited in the battery pack, with the remaining being lost to friction. If this same energy can then be extracted from the battery pack at $80\%$ efficiency, accelerating the vehicle, what will be its final speed, in mph$?($CLO $2\mathrm{.}1)$