WAEC - Mathematics (2003 - No. 16)

The sum of angles in a triangle is 180^o
2x^o + (2x -21)^o + ∠ZYP = 180^o
Also ∠ZYP = 180^o - (3x+14)^o
∴2x^o + (2x-21)^o + 180^o - (3x+14)^o = 180
x = 35^o