Answer
$ 6 \overrightarrow{i} - 3 \overrightarrow{ j}$
Work Step by Step
We can see that the notation $\lt a, b \gt $ is same as that of $a \overrightarrow{i} +b \overrightarrow{ j}$
We have: $ a= 6 $ and $b =-3$
Thus, our answer becomes:
$a \overrightarrow{i} +b \overrightarrow{ j} =6 \overrightarrow{i} +(- 3) \overrightarrow{ j}= 6 \overrightarrow{i} - 3 \overrightarrow{ j}$