find the equation the of the line parallel to y-axis and drawn through the points of intersection of the lines x-7y+5=0 and 3x+y=0

The point of intersection of the lines x-7y+5=0 and 3x+y=0 is (-5/22 , 105/152).

The abcissa of the point of intersection is -5/22.

Hence the required line passes through the point (x,y)=(-5/22 , 105/152) and is parallel to y-axis

As the equation of a line passing through (a,b) and parallel to y-axis is x=a,

The equation of the required line is x=-5/22.