It is known that AB CD and CDEF

As the angles on the same side of a transversal line sums up to 180°,

x + y = 180° .........(i)

Also,

O = z (Since they are corresponding angles)

and, y +O = 180° (Since they are a linear pair)

y + z = 180°

Now, let y = 3w and hence, z = 7w (As y : z = 3 : 7)

∴ 3w + 7w = 180°

Or, 10 w = 180°

w = 18°

y = 3×18° = 54°

and, z = 7×18° = 126°

angle x can be calculated from equation (i)

x + y = 180°

Or, x + 54° = 180°

∴ x = 126°