The number 4 is the correct answer.
Curtis has done it right because Tara forgot to put (10) and accidentally put (1) and that's where she lost herself. It wet downhill from there.
Answer:

Step-by-step explanation:
Given
Lines x and y
Transversal b

Required
Find 
From the attachment,
and
are vertically opposite.
This means that

Similarly
and
are supplementary angles
So:

Make
the subject



The relationship between
and
is that they are supplementary angles because:
