Mahad Mohammed was attacked in a housing estate in Battersea, south London, in the early hours of 22 June, last year.
A post-mortem examination the following day found he had suffered four stab wounds to his back, hip, chest and neck.
Residents were woken by the sounds of shouting and Mr Mohammed’s cries for help.
Jermaine Sawyers, 19, was told he must serve a minimum term of 20 years in prison. Cori Lindsey, 18, was sentenced to a minimum of fourteen-and-a-half years.