Answer: x = 98
=====================================================
Step-by-step explanation:
Let y be adjacent to angle x. So y = angle FGH
y is inside the triangle along with 53 and 45. The three interior angles add to 180. This is true for any three interior angles of a triangle
y+53+45 = 180
y+98 = 180
y = 180-98
y = 82
Then we can use the idea x+y = 180 to get
x+y = 180
x = 180-y
x = 180-82
x = 98
Or you could use the remote interior angle theorem. This says to add the interior angles that aren't adjacent to an exterior angle, and we get the exterior angle measure. So basically 53+45 = 98 is the measure of x.