At Think Olympics, William completes a $$1000-$$metre race. He runs the first $$540$$ metres at a speed of $$9$$ metres per second, the middle $$300$$ metres at a speed of $$6$$ metres per second, and in the final sprint stage, William runs at a speed of $$10$$ metres per second. How long did William take to finish the entire race (in seconds)? 
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