Let \( A(-1,1),\, B(3,4) \) and \( C(2,0) \) be given three points. A line \( y=mx,\, m>0 \), intersects lines \( AC \) and \( BC \) at point \( P \) and \( Q \) respectively. Let \( A_{1} \) and \( A_{2} \) be the area of \( \triangle ABC \) and \( \triangle PQC \) respectively, such that \( A_{1}=3A_{2} \), then the value of \( m \) is equal to:
