Explanation:
speed of light is 3×10^8 m/ s
1/137 of 3 × 10^ 8 m/s ( u get the speed the electron was moving with)
mass of electron 9.109× 10^-31 kg( i think we consider the mass of electron if the relativistic correction of the mass is negligible)
then from de Broglie wavelength= h/ mv
h is planck constant 6.626 × 10^-34
substitute the valies and you get the answer
am sorry I don't have my calculator with me I wuld hv written the answer bt I hope this helps