Hi Shireen,
The two vertical lines in this problem are parallel, as indicated in the diagram. If you turn your head sideways, you'll see that there is an F pattern (corresponding angles), so that means that:
(5x) + (3x + 9) = (9x - 3)
(I used parentheses above just so that you can see which angles I'm referring to.)
I'll rewrite it as:
5x + 3x + 9 = 9x - 3
If we go ahead and solve this for x, we get:
8x + 9 = 9x - 3
12 = x
Go ahead and substitute x = 12 in to the expression 3x + 9.
This will give you: 3(12) + 9 = 36 + 9
= 45 degrees
Since angle 2 and (3x+9) are vertical angles, they are congruent. That means that angle 2 also measures 45 degrees.
I hope this helps!
