Answer
$W=144 $ J
Work Step by Step
Calculate the distance between the points
$(0,10,8),(6,12,20)$
Then
$d^ {\to}=(6-0,12-10,20-8)=(6,2,12)$
$F=8i-6j+9k$
Express the force as a vector.
$F^ {\to}=\lt 8, -6, 9\gt$
As we know
Work done, $W=F^{\to}.d^{\to}$
$=\lt 8, -6, 9\gt. \lt 6,2,12\gt$
$= 8 \times 6+ (-6) \times 2+ 9\times 12$
$=48-12+108$
Hence, $W=144 $ J