SOLUTION
The principle behind the Exterior Angle Theorem is that:
the sum of two interior angles is equal to one exterior angle.
In this question, we have that :
X + ( X - 48 ) = X + 50
Collecting like terms, we have that:
2 X - 48 = X + 50
2X - X = 50 + 48
X = 98 Degrees.
CONCLUSION: The value of X = 98 Degrees.