Sum of bond order of CO and NO + is

Bond order is the number of chemical bonds between a pair of atoms and indicates the stability of a bond. 

$\mathrm{Bond} \mathrm{order}=\frac{\mathrm{Number} \mathrm{of} \mathrm{bonding} \mathrm{electrons}-\mathrm{number} \mathrm{of} \mathrm{antibonding} \mathrm{electrons}}{2}$

The given two molecules have the same number of electrons(14) like nitrogen molecule.

Hence, $\mathrm{CO}\Rightarrow \overline{\mathrm{C}}\equiv \stackrel{+}{\mathrm{O}} :\mathrm{BO}=3$

${\mathrm{NO}}^{+}\Rightarrow \mathrm{N}\equiv {\mathrm{O}}^{+} :\mathrm{BO}=3$

The sum of the bond order of $\mathrm{CO}$ and ${\mathrm{NO}}^{+}$

$$\begin{gathered} =3+3 \\ =6 \end{gathered}$$