\text { If } \underline{a}=9 \underline{i}-2 \underline{j}, \underline{b}=4 \underline{i}+5 \underline{j} \text { and } \underline{c}=-\underline{i}+2 \underline{j} \text { find (a) } \underline{a}+\underline{b} \text { (b) } \underline{b}+\underline{c}+\underline{a}(\text { c) }

\underline{a}-\underline{b}(\text { d) } \underline{c}-\underline{a}