i need to understand when reverse the equation and what equation is reversed ?

ConsiderCu2+(aq)+Zn(s)Cu(s)+Zn2+(aq)Cu2+(aq)+2eCu(s)E=+0.339VZn2+(aq)+2eZn(s)E=+0.762V Reverse the second equation (sign changes) Zn(s)Zn2+(aq)+2eE=+0.762V Combine (electrons cancel) Cu2+(aq)+Zn(s)Cu(s)+Zn2+(aq)Ecell=+1.101V E is positive so reaction is spontaneous Reverse reaction is nonspontaneous Silver does not react spontaneously with hydroge ion 2H+(aq)+2eH2(g)Ag+(aq)+eAg(s)E=0.000VE=+0.799V Reverse the second equation (sign changes) Ag(s)Ag+(aq)+eE=0.799V Multiply the second equation by 2 ( E is intensive property so remains) 2Ag(s)2Ag+(aq)+2eE=0.799V Combine (electrons cancel) 2Ag(s)+2H(t)2Ag+(aq)+H1(a)Fo= ConsiderCu2+(aq)+Zn(s)Cu(s)+Zn2+(aq)Cu2+(aq)+2eCu(s)E=+0.339VZn2+(aq)+2eZn(s)E=+0.762V Reverse the second equation (sign changes) Zn(s)Zn2+(aq)+2eE=+0.762V Combine (electrons cancel) Cu2+(aq)+Zn(s)Cu(s)+Zn2+(aq)Ecell=+1.101V E is positive so reaction is spontaneous Reverse reaction is nonspontaneous Silver does not react spontaneously with hydroge ion 2H+(aq)+2eH2(g)Ag+(aq)+eAg(s)E=0.000VE=+0.799V Reverse the second equation (sign changes) Ag(s)Ag+(aq)+eE=0.799V Multiply the second equation by 2 ( E is intensive property so remains) 2Ag(s)2Ag+(aq)+2eE=0.799V Combine (electrons cancel) 2Ag(s)+2H(t)2Ag+(aq)+H1(a)Fo=