Question
Shiyun measured and recorded the mass of Risa, Archie and Peter. The average mass of these 3 children was 51 kg. The next day, Shiyun realized that she had recorded Risa's mass wrongly. Risa's recorded mass was 9 kg more than her actual mass. What was the correct average mass of the 3 children?
3 m

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Shiyun measured and recorded the mass of Risa, Archie and Peter. The average mass of these 3 children was 51 kg. The next day, Shiyun realized that she had recorded Risa's mass wrongly. Risa's recorded mass was 9 kg more than her actual mass. What was the correct average mass of the 3 children?