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Problem 1. Calculation is incorrect. It should be redone.
Problem 2. Correct.
Problem 3. Correct.
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Comment from student: Thank you so much for quick response. On Problem 1 I made mistake - it should be 90 kg - 0.518 kg = 89.482
Could you verify that this subtraction problem above is correct? Thanks so much
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My response : This simple arithmetic is done correctly.