Embedding of absolutely free groups into groups $B(m,n,1)$

In this paper we prove that each countable absolutely free group can be isomorphic embedded into groups$B(m,n,1)$ for arbitrary $m \ge 2$ and odd $n \ge 665$. Thereby is shown that each group $B(m,n,1)$ generates the variety of all groups, and groups $B(m,n,1)$ are non-amenable. Particularly Tarski’s number is equal to $4$.