Since they are regular polygons all their internal angles are equals

Internal Angle of Pentagon = $108^o$
Internal Angle of Hexagon = $120^o$

Triangle formed by the line m, the Hexagon and line connecting the two polygons is an equilateral triangle.
Its hard to explain since the diagram hasn't named the points.

Now, the triangle formed by line l, the Pentagon and line connecting the two polygons -

The angle just above $x$ is equal to $180^o - 108^o = 72^o$

The angle formed by intersection of line l and joining-line will be $60^o$

So $x^o + 72^o + 60^o = 180^o$

$x^o = 180^o - 132^o =$ $48^o$