Solve the equation:
\[
  \sin 9^\circ \sin 21^\circ \sin(102^\circ + x^\circ) = \sin 30^\circ \sin 42^\circ \sin x^\circ
\]
for \(x\) where \(0 < x < 90\).

Let's think step by step and output the final answer within \boxed{}.
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