  Using the tool of unitary transformations of the extended receiver we perform
simple operations with the non-diagonal elements of the initial sender's
density matrix after their transferring to the receiver. These operations are
following: turning some matrix elements to zero, rearranging the matrix
elements and preparing their linear combinations with required coefficients. We
also propose a protocol for solving a system of linear algebraic equations with
a system of two equations as an example. Such operations are numerically
simulated on the basis of 42-node spin-1/2 chain with the two-qubit sender and
receiver.
