$$\eqalign{
A\left( {2;1} \right) & ,\,\,B\left( {0;5} \right),\,\,C\left( {8;7} \right) \cr
a)\,\,\overrightarrow {AB} = \left( { - 2;4} \right);\,\,\overrightarrow {CA} = \left( { - 6; - 6} \right) \cr
\Rightarrow \overrightarrow {AB} + \overrightarrow {CA} = \left( { - 8; - 2} \right) \cr
\overrightarrow {CA} = \left( { - 6; - 6} \right);\,\,\overrightarrow {CB} = \left( { - 8; - 2} \right) \cr
\Rightarrow \overrightarrow {CA} + \overrightarrow {CB} = \left( { - 14; - 8} \right) \cr
\overrightarrow {AB} = \left( { - 2;4} \right);\,\,\overrightarrow {AC} = \left( {6;6} \right) \cr
\Rightarrow \overrightarrow {AB} + \overrightarrow {AC} = \left( {4;10} \right) \cr
\overrightarrow {AB} = \left( { - 2;4} \right) \cr
\overrightarrow {BC} = \left( {8;2} \right) \cr
\Rightarrow \overrightarrow {AB} - \overrightarrow {BC} = \left( { - 10;2} \right) \cr
2)\,\,3\overrightarrow {AB} = 3\left( { - 2;4} \right) = \left( { - 6;12} \right) \cr
\,\,\,\,\,\,2\overrightarrow {CA} = 2\left( { - 6; - 6} \right) = \left( { - 12; - 12} \right) \cr
\,\,\,\,\,\,5\overrightarrow {BC} = 5\left( {8;2} \right) = \left( {40;10} \right) \cr
3)\,\,3\overrightarrow {AB} + 2\overrightarrow {CA} = 3\left( { - 2;4} \right) + 2\left( { - 6; - 6} \right) \cr
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \left( { - 6;12} \right) + \left( { - 12; - 12} \right) = \left( { - 18;0} \right) \cr
\,\,\,\,\,5\overrightarrow {BC} + 3\overrightarrow {AB} = 5\left( {8;2} \right) + 3\left( { - 2;4} \right) = \left( {34;22} \right) \cr
\,\,\,\,4\overrightarrow {BC} - 2\overrightarrow {AB} = 4\left( {8;2} \right) - 2\left( { - 2;4} \right) = \left( {36;0} \right) \cr} $$
