Elimination reaction with 1,2-dibromo-4-methylcyclohexane
Dehalogenation of vicinal dihalides by iodide ion occurs stereospecifically and
  concertedly via an $\mathrm{E2}$ mechanism. An anti-coplanar arrangement of both bromine atoms is required (see diagram below):




Since, the given compound is a 1,2-trans-dibromocyclohexane, two bromo groups  can arrange in 1,2-anti-diaxial positions in one of chair confirmations, fulfilling the requirement. It won't be possible if it'd have been a 1,2-cis-dibromocyclohexane.

Reference: Structure &amp; Synthesis of Alkenes (Chapter 7): Leroy G. Wade, Organic Chemistry; 8th Edn, Pearson Education Limited: Harlow, Essex, UK, 2014.