Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$-12-5i$
Removing the grouping symbols and then adding the real parts and the imaginary parts, the given expression, $(-5-i)-(7+4i) ,$ simplifies to \begin{array}{l}\require{cancel} -5-i-7-4i \\\\= (-5-7)+(-i-4i) \\\\= -12-5i .\end{array}