Answer:
C.
Step-by-step explanation:
Recall that the sum of the (3) interior angles of a triangle <em>must</em> equate to 180.
In other words:
Where x is our unknown angle. So, we need to solve for x.
On the left, add 55 and 20:
Subtract 75 from both sides. The left side cancels:
Therefore, the third angle is 105 degrees.
Our answer is C.