This image
becomes a real object for the second lens: f2 = + 30 cm, u2 =
– (20 + 8) cm = – 28 cm which gives, v2 = – 420 cm The parallel
incident beam appears to diverge from a point 416 cm on the
left of the centre of the two-lens system Clearly, the answer depends on which side of the lens system
the parallel beam is incident Further we do not have a simple lens
equation true for all u (and v) in terms of a definite constant of the
system  (the constant being determined by f1 and f2, and the separation
between the lenses)