JAMB - Mathematics (1987 - No. 45)

Z = X = Y = 180^o .........(i)

2Z + Y + Y = 190 = 2Z + 2Y = 180

Z + Y = 90^o........(ii)

hence x + (z + y) = 180

x + 90^o = 180^o

x = 180^o - 90^o

= 90^o