Answer:
The exact speed at which this occurs will depend on the wavelength in question. In general, the de Broglie wavelength of a particle is given by the following equation:
wavelength = h / (m * v)
where h is Planck's constant, m is the mass of the particle, and v is the particle's speed. In order to find the speed at which a proton and an electron will have the same de Broglie wavelength, you would need to know the values of h, m, and the desired wavelength.