Answer:
D. 85
Step-by-step explanation:
The sum of the interior angles of a triangle is equal to 180. Since we already know 2 of the interior angles of that triangle (40 and 55), we can subtract those two angles from 180 to find x.
180 - 40 - 55 = 85
85 degrees
All angles in a triangle must add up to 180, so we can set up an equation
x+40+55=180
Now all we need to do is to subtract 40 and 55 from both sides
x+55=180-40=140
x=140-55=85
x=85
