Va rog mult. Problema din poza. Urgent

Es=nE=3E
rs=nr=3r
Ep=E
rp=r/n=r/3
Ip=Ep/(R+rp)=E/(R+r/3)
Is=Es/(R+rs)=3E/(R+3r)
Ip=Is=>E/(R+r/3)=3E/(R+3r)<=>1/(R+r/3)=3/(R+3r)=>R+3r=3R+r<=>-2R=-2r |:r=>R/r=1