We know that $\mathbf{u}=2\mathbf{i}-\mathbf{j}$ and $\mathbf{w}=\mathbf{i}+2\mathbf{j}$, so we can substitute these into the equation:
\begin{align*}
3\mathbf{u}+\mathbf{w} &= 3(2\mathbf{i}-\mathbf{j}) + (\mathbf{i}+2\mathbf{j}) \\
&= 6\mathbf{i}-3\mathbf{j} +
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