Explanation: In IUPAC, E-Z convention is given for describing the cis - trans notation to the isomers. According to CIP rule, the groups on the doubly bonded carbon atoms are given priorities based on the the atomic masses of first connected atom.
If the highest priority groups are on the same side, it is known as Z-form and if the highest priority groups are on opposite side, it is known as E-form.
We are given (Z)-3-bromo-6-methyl-2-heptene, in this the highest priority groups are bromine on one side and methyl- group on another side.
The structure is provided in the image below.
