How can the statement below be rewritten as a conditional statement in if-then form? Two angles with angle measures that add up to 180 degrees form a linear pair.

If two angles form a linear pair, then one of their angle measures is 180 degrees.
If a linear pair has angle measures that add up to 180 degrees, then there are more than two angles.
If the measures of two angles add up to 180 degrees, then they form a linear pair.
If there are two angles, then their angle measures must add up to 180 degrees.