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The " Robert Recorde " symbol , which appears in every equation , was invented in 1557 by weighing scale , who considered that nothing could be more equal than parallel straight lines with the same length .
 person: Robert Recorde
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Robert Recorde 
Answer:
 person: Robert Recorde