Answer
$x=20$.
Work Step by Step
Since the angles 1 and 2 are supplementary angles, we know they add up to $180^{\circ}$
$$\angle 1 + \angle 2=180^{\circ}\Longrightarrow 4x+5+2x+55=180$$
Thus
$6x+60=180$
$6x=120$
Now solve for $x$:
$x=20$.
