Let the required page numbers are x and ( x + 1 ) ,
Given that the sum of page numbers is 517
According to the question :
= > x + ( x + 1 ) = 517
= > x + x + 1 = 517
= > 2x = 517 - 1
= > 2x = 516

= > x = 258
Therefore,
Page numbers are ( x = 258 ) and ( x + 1 = 258 + 1 = 259 )