An electron practically at rest is initially accelerated through a potential difference of 100volts . It then has a de-Broglie wavelength $={\mathrm{\lambda }}_1^0\mathrm{A}$. It then gets retarded through 19 volts and then has a wave length $={\mathrm{\lambda }}_2^0\mathrm{A}$. A further retardation through 32 volts changes the wavelength to $={\mathrm{\lambda }}_3^0\mathrm{A}\text{ is }\frac{{\mathrm{\lambda }}_3-{\mathrm{\lambda }}_2}{{\mathrm{\lambda }}_1}\text{ is }\frac{\mathrm{x}}{\mathrm{y}}$ then $\frac{\mathrm{y}}{\mathrm{x}}$ is