Potassium dichromate, ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. 

The balanced reaction is,

${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}+14{\mathrm{H}}^{+}+6{\mathrm{e}}^{-}\to 2{\mathrm{Cr}}^{3+}+7{\mathrm{H}}_2\mathrm{O}$

$\mathrm{X}=14$

$\mathrm{Y}=6$

$\mathrm{A}=7$