Answer:
The equation of the fourth line is;

Step-by-step explanation:
Given that the fourth line would also be parallel to the other three lines.

And passes through the point;

Since, we have the value of the slope and we have a point on the fourth line;
Then we can use the point-slope form;

substituting the given values;

Therefore, the equation of the fourth line is;

To derive the equation of the fourth line, the best and easiest equation to use is the point-slope form. because we were given the slope and a point on the slope.