Answer
$[6, -2]$
Work Step by Step
To add or subtract vectors, one can only combine components of like position with each other. Thus, we add the second component of d and the second component of a, and we add the first component of d and the first component of a to obtain:
$a=[3, 0]$ and $d=[3, -2]$
$a+d=[(3+3), (0+(-2))]=[6, -2]$