Remove the 7k ohm, since it is not part of the circuit we wish to simplify. Keep the terminals open since we are finding the Thevenin. First, find Vth, the voltage across the terminals (in this case it is the voltage over the 3k ohm). I would combine the 2k and 1k in parallel and then use a voltage divider. Second, find Rth by deactivating the source (short voltage sources).
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