Answered By Lohrasp S

If the slope of the lines are equal to one another, then the lines are parallel.

Answered By Kevin G

If the equations of the line are in the form 

 $y=mx+b$y=mx+b 

or

 $y-y_1=m\left(x-x_1\right)$y−y₁=m(x−x₁) 

where m, b, x_1 and y_1 are just placeholders for numbers,

then the lines are parallel if the value of 'm' is the same number in both equations.