Answer
(a) $W= 12.0 J$
(b) $W= 0J$
Work Step by Step
(a)$W =\vec F . \Delta\vec r $
$W= ( -4.0 \vec i -6.0 \vec j)N.( -3.0 \vec i )m$
$ W =(-4.0×-3.0 )J+( -6.0×0) J $
$W= 12.0 J$
(b) $W =\vec F . \Delta\vec r $
$W= (-4.0 \vec i -6.0 \vec j)N.(3.0 \vec - 2.0 \vec j )m$
$ W =( -4.0×3.0 )J+(-6.0×-2.0 ) J $
$W= -12.0J +12.0J $
$W= 0J$
