SOLUTION: A total of four hundred people attended the local symphony's holiday concert at the civic center. The admission prices were $12 for adults, $9 for high school students, and $5 for

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Question 1058127: A total of four hundred people attended the local symphony's holiday concert at the civic center. The admission prices were $12 for adults, $9 for high school students, and $5 for children. The ticket sales totaled $3215. The symphony's director suggested that next year they raise the prices to $15 for adults, $10 for high school students, and $6 for children. She said that if the same number of people attended next year, the ticket sales at the higher price will total $3817. How many adults, high school students, and children attended THIS YEAR?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
y adults, s students, c children;

This year: system%28y%2Bs%2Bc=400%2C12y%2B9s%2B5c=3215%29

Next year: 15y%2B10s%2B6c=3817

Arrange this system and try to use row reduction of the system as a matrix:
system%28y%2Bs%2Bc=400%2C12y%2B9s%2B5c=3215%2C15y%2B10s%2B6c=3817%29.