1003047806

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Project ID: 
1003047806
Accepted: 
1
Clonable: 
0
Easy: 
0
Every school must pay a registration fee for each participant it sends to a math competition. The fee for the first participant is $10$ euros, for each additional one the fee is one euro less. The maximum number of participants any school can register is $10$. Find the relationship between the price ($c$) paid by the school and the number of students registered ($n$).
$c=\frac n2(21-n)$
$c=10-\frac{n^2}2$
$c=\frac{11n}2$
$c=\frac n2(10+10n)$
$c=\frac n2(11-n)$