Consider the following sets:
u = {points on the coordinate plane}
a = {solutions to the equation y = 2x + 5}
b = {points on the line y = mx}
for what value of m does a ∩ b = ∅?
m =

U = {points on the coordinate plane}
A = {solutions to the equation y = 2x + 5}
B = {points on the line y = mx}

Value of the slope m so that  {2x + 5} ∩ {mx} =Ф
This means that {2x + 5} never intersects with {mx}
To that end m=2 (same slope), if so the 2 linear functions:

y = 2x+5 and y = 2x are PARALLEL