So basically what you can do is first find the measures of the interior angles inside the triangle.
Since you know that a straight line has an angle measure of 180 degrees, you can use that info to figure out the interior angles.
For the 140 degrees angle, it lays on a straight line with a measure of 180 degrees. You want to find how much of that isn't taken up by that 140 degrees angle, by subtracting 140 from 180.
180 - 140 = 40
So the interior angle pictured at the very top is 40 degrees.
Do the same for the 113 degrees angle one.
180 - 113 = 67
So now you know those two interior angles are 67 and 40.
For a triangle, the interior angles must add up to 180 degrees.
So we can find the other angle in the triangle through that logic.
So we know:
67 + 40 + other angle = 180
or,
107 + other angle = 180
-107 -107
other angle = 73
So we know the other angle is 73 degrees. By the logic of a straight line being 180 degrees, we can then figure out that the angle x is also 73 degrees.
(180 - 73 = 107, 180 - 107 = 73)
So your answer is 73 degrees.