Answer:
a) Angle XBC = 55 because XY is parallel with BD
b) As given, XB = XC, so that triangle XBC is the equilateral triangle.
As XBC is equilateral triangle, angle XBC is equal to angle XCB
Angle XBC = 55° => Angle XCB = 55°
In a triangle, the total value of three corners are equal to 180°
So that: Angle XBC + Angle XCB + Angle BXC = 180°
=> 55° + 55° + Angle BXC = 180 °
=> Angle BXC = 70°
2/7x - 2/5x = 8
multiply both sides by 35
= 10x - 14x = 280
combine 10x and 14x
= -4x = 280
divide both sides by -4
x= -70