Answer
(a) $U+V=(4,0)$
(b) $U-V=(-12,-8)$
(c) $-U=(4,4)$
Work Step by Step
$U=(-4,-4)$
$V=(8,4)$
(a)
$U+V=(-4,-4)+(8,4)$
$U+V=(-4+8,-4+4)$
$U+V=(4,0)$
(b)
$U-V=(-4,-4)-(8,4)$
$U-V=(-4-8,-4-4)$
$U-V=(-12,-8)$
(c)
$-U=-1\times (-4,-4)=(4,4)$