The total number of alkenes possible by dehydrobromination of 3-bromo-3-cyclopentylhexane using alcoholic $\mathrm{KOH}$ is

The substrate has three different types of $\mathrm{B}-\mathrm{H}$, therefore, first, three structural isomers of alkenes are expected as
The last two alkenes II and III are also capable of showing geometrical isomerism hence two geometrical isomers for each of them will be counted giving a total of five isomers.