On the supersoluble residual of a product of subnormal supersoluble subgroups

We give a sufficient condition for supersolubility of a finite group that is a product of two subnormal supersoluble subgroups. We prove that the supersoluble residual of such a group is equal to its nilpotent residual. Also we apply these results to finite groups that are a product of two subnormal $p$-supersoluble subgroups.