You try a few.

Find the distance between each pair of lines.

1.)       

y = -3x + 1
y = -3x - 2

[Click for answer to #1]

2.)       

y = -1/2x + 2
y = -1/2x + 1

[Click for answer to #2]

3.)      

4y - 3x = 12
4y - 3x = -8

[Click for answer to #3]

Created by Mathematica  (December 3, 2004)