$$\overrightarrow {PQ}$$ has components $$\left( \begin{array}{l} 2\\ 5 \end{array} \right)$$
$$\overrightarrow {QR}$$ has components $$\left( \begin{array}{l} 4\\ -3 \end{array} \right)$$
When we add these vectors the result is $$\overrightarrow {PQ} + \overrightarrow {QR} = \overrightarrow {PR}$$
Adding the components follows the rule $$\left( \begin{array}{l} a\\ b \end{array} \right) + \left( \begin{array}{l} c\\ d \end{array} \right) = \left( \begin{array}{l} a + c\\ b + d \end{array} \right)$$
So $$\overrightarrow {PQ} + \overrightarrow {QR} = \overrightarrow {PR}$$ looks like this, $$\left( \begin{array}{l}2\\5\end{array} \right) + \left( \begin{array}{l}4\\-3\end{array} \right) = \left( \begin{array}{l}6\\2\end{array} \right)$$