Given $$A = \left[\begin{array}{cc} -3 &-15\cr 1 &5\cr -2 &-10 \end{array}\right],$$ find one nontrivial solution of $A\vec{x}=\vec{0}$ by inspection.

$\vec{x} =$ $\left[\Rule{0pt}{2.4em}{0pt}\right.$$\left]\Rule{0pt}{2.4em}{0pt}\right.$