Answer:
The answer is option A.
∆BDC is a right angled triangle
Angles in a triangle add up to 180°
That's
z + 35 + 90 = 180°
z = 180 - 35 - 90
z = 55°
Alternate angles are equal
Angle DBC = Angle BDA
That's
35 = 7y
Divide both sides by 7
y = 5
y = 5 z = 55
Hope this helps you
