Answer
An elimination reaction occurs.
Work Step by Step
$(CH_3CH_2)_3N:$ is a strong base, so it gives a second order reaction. Since the reactant is a 3∘ alkyl halide, it prevents a $S_N2$ reaction, so the $E2$ reaction is the only option. Since the base is very hindered, it gives the less substituted double bond as the major isomer.