Find the maximum fractional energy loss $(\backslash$Delta E$/$E$),$ for E$=0\mathrm{.}68$MeV gamma ray that is Compton scattered from a free electron. State your answer to the nearest thousandth of a unit.$\backslash$

Take Planck's constant to be h $=6\mathrm{.}626*10-34$ J$$s$,$ the speed of light to be c $=3*108$ m$/$s$,1$eV $=1\mathrm{.}602*10-19$ J$,$ and the mass of an electron to be me $=9\mathrm{.}11*10-31$ kg$=0\mathrm{.}511$MeV$/$c$2$