Answer: B. x = 40
Step-by-step explanation:
The angles given are supplementary.
Supplementary angles are any two angles that add to 180 degrees, most commonly seen on one side of a straight line.
As these angles are supplementary, we can solve for x by adding both angles to get 180:
[tex](3x + 15) + 45 = 180\\\\3x + 60 = 180\\\\3x = 120\\\\x = 40[/tex]
This means that the angle on the left is (3*40) + 15, or 135 degrees, while the angle on the right is 45 degrees. These angles add to 180 degrees.
The correct answer choice is B.
