Help! Angles quiz answer problem!?

Question

Hey, the first question to this quiz:

http://teachers.henrico.k12.va.us/math/igo/01Fundamentals/1-5PairsofAngles/1_5AngPairs.htm

Says that the answer to number 1 is "A"

I put "C" and I don't get why I'm wrong... Could someone enlighten me?

Answer 1

You aren't wrong the test is.

7x-8=6x+11

x-8=11

x=19

Answer is indeed C.