Question

What’s the approximate distance?

Answer 1

Let m be the slope of the parallel lines, each having a slope of m
Then the distance between the parallel lines 
= (difference in y-intercept)/sqrt(1+m^2)

For the given problem,
difference in y-intercept = 4-2=2
slope = m = -1
Distance between lines = 2/sqrt(1+(-1)^2) =2/sqrt(2)=sqrt(2)=1.41421

Answer: distance between the parallel lines = 1.41 (to the nearest hundredth)