Correct approach: The gear with 48 rotations/min makes a rotation every $ \frac{1}{48} $ minutes. The other every $ \frac{1}{72} $ minutes. They align when both complete integer numbers of rotations and the total time is the same. So $ t $ must satisfy $ t = 48 a = 72 b $ for integers $ a, b $. So $ t = \mathrm{LCM}(48, 72) $.

Tue, 05 May 2026 03:47:31 +0000

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