Answer
$x=2+3t,y=4+7t, z=5-5t$
Work Step by Step
As we know the parametric equations of a straight line for a vector $v=v_1i+v_2j+v_3k$ passing through a point $P(a,b,c)$ is given by
$x=a+t v_1,y=b+t v_2; z=c+t v_3$
Since, we have the vector $v=\lt 3,7,-5 \gt$ is perpendicular to the plane at point $P(2,4,5)$.Then our parametric equations are:
$x=2+3t,y=4+7t, z=5-5t$