it is simple, the matrix is distributive.
a(bk)=ab(K). the variable k is 14.
i suggest this matrix;
{a1n a2n a10} by {a6 a10} by {1 1}
{a1 a2 a5} {1 1} {1 sigma 50}.
these reduces the matrix to an equivalent cofactors to determine the
associated elements.