We know that the opposite angles of a cyclic quadrilateral are supplementary, therefore,
∠A + ∠C = 180°
=> 2x+4 + 4y + 4 = 180
=> 2x + 4y = 172......(1) Dividing by 2
=> x +2y= 86
and ∠B + ∠D = 180°
=> x+10 + 5y + 5 = 180
=> x +5y = 165....(2)
(2) -(1) => 3y = 79
y= 79/3 = 26.3
Substituting y= 79/3 in (1)
We get x = 33.3