The stereochemistry of the double bonds in the product is

Concept:

The 1,7-sigmatropic rearrangement, often referred to as a [1,7]-sigmatropic rearrangement, is a type of pericyclic reaction in organic chemistry. In this rearrangement, a sigma (σ) bond between two carbon atoms separated by six intervening carbon atoms (hence, a 1,7-bond) shifts, resulting in the migration of substituents and the formation of a new sigma bond.

Explanation:

⇒The reactant undergoes 1,7-sigmatropic rearrangement in the presence of heat as follows-
 

⇒Stereochemistry of the product-

On C-3 and C-5 atoms the higher priority groups are both on the same side of the double bond. Therefore, alkenes on position 3 and 5 are Zusammen i.e. Z.

On C-7 the higher priority groups are on the opposite side of each other of the double bond. Therefore, alkene on position 7 is Entgegen i.e. E.

Conclusion:

Hence, the stereochemistry of the double bonds in the product is 3Z, 5Z, 7E