71 and the blank angle are a linear pair/supplementary angles, meaning that their sum is 180 degrees.
71 + y = 180
y = 109
The sum of the interior angles of a triangle is 180 degrees. Therefore, all of the angles inside of the triangle will add up to 180.
109 + 46 + x = 180
x = 25
Answer: x = 25 degrees
Hope this helps!