已知向量\( \overrightarrow{a}=m \overrightarrow{i}+5 \overrightarrow{j}- \overrightarrow{k}, \overrightarrow{b}=3 \overrightarrow{i}+ \overrightarrow{j}+r \overrightarrow{k} \)，若\( \overrightarrow{a} /\!/ \overrightarrow{b} \)则实数\(m\)\(= \)______，\(r\)\(= \)______．