In the given figure :
Line WY divide the angle XYZ
So, Angle XYZ = Angle XYW and Angle WYZ
From the given data : ANgle XYW = 59, Angle WYZ = 3x + 15
Substitute the values and simplify :
Angle XYZ = Angle XYW + Angle WYZ
149 = 59 + (3x + 15)
Simplify the expression for x :
149 = 59 + (3x + 15)
149 - 59 = 3x + 15
90 = 3x + 15
3x = 90 - 15
3x = 75
x = 75/3
x = 25
ANswer : x = 25