Answer
$(-6,-5)\cdot(10,-12)=-6(10)-5(-12)=0$
Work Step by Step
If the vectors are perpendicular, their dot product must be zero.
Dot product$=(-6,-5)\cdot(10,-12)=-6(10)-5(-12)=-60+60=0$.
Therefore, $-6\textbf {i}-5\textbf {j}$ and $10\textbf {i}-12\textbf {j}$ are perpendicular.