Q: What is the result of 21 minus 13? A: 
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Q: What is the result of 28 minus 13? A: 
Q: What is the result of 21 minus 10? A: 
Q: What is the result of 21 minus 13? A: 
Q: What is the result of 21 minus 13? A: 
Q: What is the result of 28 minus 10? A: 
Q: What is the result of 21 minus 13? A: 