So all of the internal angles of a triangle will add up to 180 degrees. So if we add all of the expressions given and set them equal to 180, we can solve for x, then solve for each angle...
Now we can substitute 13 into each expression to find the value of each angle...
2x + 1 = 2(13) + 1 = 26 + 1 = 27 degrees
3x - 3 = 3(13) - 3 = 39 - 3 = 36 degrees
9x = 9(13) = 117 degrees
So the 3 angles are 27 degrees, 36 degrees, and 117 degrees.
The smallest is 27 degrees
** Note-- I don't see 27 degrees in the answer choices you gave, so I double checked my math (I didn't find any mistakes). Please check to see that the question is written correctly (pay close attention to plus and minus signs).
