By a writing, an owner leased his house to a tenant for a term of three years, ending December 31 of last year, at the rent of $1,000 per month. The lease provided that the tenant could sublet and assign. The tenant lived in the house for one year and paid the rent promptly. After one year, the tenant leased the house to his friend for one year at a rent of $1,000 per month. The friend took possession of the house and lived there for six months but, because of her unemployment, paid no rent. After six months, on June 30, the friend abandoned the house, which remained vacant for the balance of that year. The tenant again took possession of the house at the beginning of the third and final year of the term but paid the owner no rent. At the end of the lease term, the owner brought an appropriate action against both the tenant and his friend to recover $24,000, the unpaid rent. In such action the owner is entitled to a judgment