  This paper presents the reduced biquaternion mixed least squares and total
least squares (RBMTLS) method for solving an overdetermined system $AX \approx
B$ in the reduced biquaternion algebra. The RBMTLS method is suitable when
matrix $B$ and a few columns of matrix $A$ contain errors. By examining real
representations of reduced biquaternion matrices, we investigate the conditions
for the existence and uniqueness of the real RBMTLS solution and derive an
explicit expression for the real RBMTLS solution. The proposed technique covers
two special cases: the reduced biquaternion total least squares (RBTLS) method
and the reduced biquaternion least squares (RBLS) method. Furthermore, the
developed method is also used to find the best approximate solution to $AX
\approx B$ over a complex field. Lastly, a numerical example is presented to
support our findings.
