Adjacent angles of a parallelogram are supplementary.
In parallelogram RISK, ∠RKS + ∠ISK = 180°
120° + ∠ISK = 180°
∠ISK = 60°
Also, opposite angles of a parallelogram are equal.
In parallelogram CLUE, ∠ULC = ∠CEU = 70°
The sum of the measures of all the interior angles of a triangle is 180º.
x + 60° + 70° = 180°
x = 50°