You can put this solution on YOUR website! A line on a xy graph only intercepts the y-axis when x=0.
A straight line on a xy graph has the equation y=mx+c, for the equation y=-2, m=0 and c=-2: y=0x-2.
So when x=0 the line intersects the y-axis, substitute the values and the line y=0(0)-2 must intersect the y-axis at -2.