SOLUTION: in a class of 42 pupils 7 more pupils received b than a on a test and the number who had c was 3 times the number whop had a, find the number of pupils receiving each mark

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Question 907573: in a class of 42 pupils 7 more pupils received b than a on a test and the number who had c was 3 times the number whop had a, find the number of pupils receiving each mark
Answer by rfer(16322) About Me  (Show Source):
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a=a
b=a+7
c=3a
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a+a+7+3a=42
5a=42-7
5a=35
a=35/5
a=7
a+7=14
3a=21