The wavelength of an electron and a neutron will become equal when the velocity of the electron is x times the velocity of neutron. The value of x is (Nearest Integer) (Mass of electron is $9.1\times {10}^{-31}\mathrm{kg}$ and mass of neutron is $1.6\times {10}^{-27}\mathrm{kg}$ )

$\text{Using relation, }\mathrm{\lambda }=\frac{\mathrm{h}}{\mathrm{mv}}$
$\begin{array}{l} \\ {\mathrm{\lambda }}_{\text{electron }}=\frac{\mathrm{h}}{9.1\times {10}^{-31}\mathrm{kg} .(x\cdot {\mathrm{v}}_{\text{neutron }})} ...\left(\mathrm{i}\right)\\ {\mathrm{\lambda }}_{\text{electron }}=\frac{\mathrm{h}}{1.6\times {10}^{-27}\mathrm{kg}\cdot {\mathrm{v}}_{\mathrm{neutron}} } ...\left(\mathrm{ii}\right)\\ \end{array}$
$\begin{array}{l}\text{ Equating (i) and (ii), }\\ \frac{\mathrm{h}}{9.1\times {10}^{-31}\mathrm{kg} (x\cdot {\mathrm{v}}_{\text{neutron }})}=\frac{\mathrm{h}}{1.6\times {10}^{-27}\mathrm{kg}\cdot {\mathrm{v}}_{\text{neutron }}}\\ \mathrm{x}=\frac{1.6\times {10}^{-27}}{9.1\times {10}^{-31}}\Rightarrow \mathrm{x}=0.17582\times {10}^4=1758.2\end{array}$