Total of the 6 lawna = 10 + 15 + 12 + 15 + 8 + 15 = $75
Given that the mean is $12 for 7 lawns,
Total of the 7 lawns = 12 x 7 = $84
Therefore the 7th lawn is:
$84 - $75 = $9
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Answer: He earns $9 on the 7th lawn. (Answer A)
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