Given the lines ab and cd, determine the slope of line cd.

You have not provided the coordinates, therefore, I can only help you with the concepts.

1- If the coordinates of C and D are given:
If the coordinates of C and D are given as:
C = (x₁,y₁)
D = (x₂,y₂)
We can simply get the slope using the following formula:
slope = 

2- If the coordinates of A and B are given along with a relation between the two lines:
a- We will get the slope of AB  using the formula above
b- If we are given that AB is parallel to CD, then:
slope of CD = slope of AB
c- If we are given that AB is perpendicular to CD, then:
slope of CD = 1 / (slope of AB)

Hope this helps :)