An astronaut in his space suit and with a propulsion (empty of gas propellant) stapped to his back has a mass of 146kg. during a space walk, the unit, which has been completely filled with propellant gas, ejects some gas with a velocity of +32m/s. as a result, the astronaut recoils with a velocity of -.39m/s. After the gas is ejected, the mass of the astronaut (now wearing an partically empty propullsion tank) is 165kg. what percentage of the gas propellant in the completely filled propulsion unit was depleated?