The de Broglie wavelength of a particle is given by the formula:

$$\lambda = \frac{h}{p}$$

where $h$ is Planck's constant and $p$ is the momentum of the particle.

If the de Broglie wavelengths of the proton and electron are the same, then:

$$\frac{h}{p_p} = \frac{h}{p_e}$$

where $p_p$ and $p_e$ are the momenta of the proton and electron, respectively.

Solving this equation for the ratio of their momenta gives:

$$\frac{p_p}{p_e} = 1$$

So, the ratio of their momenta is 1:1