Answer: X = 17
Step-by-step explanation: The line shows three different angles labeled as AED, CEA, and CEF. However angle CED is an addition of the angles CEA and AED. Therefore to calculate CED,
Angle CED = Angle CEA + angle AED
Angle CED = 6X - 20 + 3X + 18
Angle CED = 9X -2
However, angle CED is given as 151. Hence,
151 = 9X - 2
Add 2 to both sides of the equation
153 = 9X
Divide both sides of the equation by 9
17 = X