Answer
Mass defect= 1.16754 amu
Nuclear binding energy= 8.431 MeV/nucleon
Work Step by Step
Mass defect=[Z(mass $^{1}_{1}H$)+(A-Z)(mass $^{1}_{0}n$)]-mass $^{129}_{54}Xe$
=54(1.00783 amu)+75(1.00866 amu)- 128.904780 amu
=1.16754 amu.
Nuclear binding energy=$1.16754\,amu\times\frac{931.5\,MeV}{1\,amu}=1087.56\,MeV$
Nuclear binding energy per nucleon=
$\frac{Binding\,energy}{A}=\frac{1087.56\,MeV}{129\,nucleons}=8.431\,MeV/nucleon$
