Let's call the number you thought of n. Then what the two steps you took can be written as an equation:

Subtract n to get all of your variables to one side:

At this point, I recommend turning your mixed number into an improper fraction. It will make things easier later on:

Now divide both sides by 11 to get the value of n:
Answer:
C. 15
Step-by-step explanation:
<h2>
<em><u>∠ADC=∠ABC/2=30/2=15</u></em></h2>
Answer:
x-15
Step-by-step explanation:
The answer is 27 I believe