SOLUTION: In a classroom, there are 54 chairs. The number of chairs per row is three less than twice the number of rows. Find the number of rows and the number of chairs per row.

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: In a classroom, there are 54 chairs. The number of chairs per row is three less than twice the number of rows. Find the number of rows and the number of chairs per row.      Log On


   

Question 983059: In a classroom, there are 54 chairs. The number of chairs per row is three less than twice the number of rows. Find the number of rows and the number of chairs per row.
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
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c=chairs per row; r=number of rows
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c=2r-3
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(c)(r)=54
(2r-3)(r)=54
2r^2-3r=54
2r^2-3r-54=0
(2r+9)(r-6)=0
2r+9=0 OR r-6=0
r=-4.5 OR r=6
ANSWER 1: There are 6 rows (-4.5 makes no sense)
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c=2r-3
c=2(6)-3=12-3=9
ANSWER 2: There are 9 chairs per row
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CHECK:
(6 rows)(9 chairs/row)=54 chairs
54 chairs=54 chairs