( С₆₄ ⁴² - С₆₅ ⁴³ ) / С₆₂ ²² =
= ( 64 ! / (64 - 42)!*42! - 65! / (65 - 43!)*43! ) / ( 62! / (62 -22)!*22! ) =
=( 64 ! / 42!*22! - 65! / 43!*22!* ) / ( 62! / 40!*22! ) =
= ( 64 ! / 42 ! - 65 ! / 43 ! ) / ( 62 !/*40! ) =
=(64 ! / 42 ! ) *(1 -65/43) / (62! /40!) = 63*64*(- 22/43) / (41*42 ) = - 3*3*7*64*2*11 / 41*42*43 = - 3*64*11 / 41*43 =-2112 / 1763.