Chapter 8 - Review Exercises - Page 618: 94

$W=72$

Let $u$ be the vector from $P$ to $Q$ $u=(-12,8)-(-2,-9)=[-12-(-2),-9-8)=(-12+2,-9-8)=(-10,-17)=-10i=17j$ Now, let's find the dot product of $u$ and $v$: $W=u.v=(-10i-17j)(3i-6j)=-10\times3-17\times(-6)=-30+102=72$