Answer:
If lines have the same slope, then they are parallel.
Explanation:
The first part of the given statement sets up the condition for the second part to be true. A conditional statement makes that explicit.
(lines described by first part) are (lines described by second part) ⇒
if (lines are described by first part), then (lines are described by second part)
Your conditional statement can be written ...
If lines have the same slope, then they are parallel.