SOLUTION: Please help! A room contains 78 chairs arranged in rows. The number of rows is one more than twice the number of chairs per row. Find the number of rows.

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: Please help! A room contains 78 chairs arranged in rows. The number of rows is one more than twice the number of chairs per row. Find the number of rows.      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 953527: Please help!
A room contains 78 chairs arranged in rows. The number of rows is one more than twice the number of chairs per row. Find the number of rows.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A room contains 78 chairs arranged in rows. The number of rows is one more than twice the number of chairs per row. Find the number of rows.
----
Let the number of rows be "r".
Let the number of chairs in a row be "c"
----------------
Equations:
c*r = 78
r = 2c+1
----
Substitute for "r" and solve for "c":
c(2c+1) = 78
2c^2 + c - 78 = 0
-----
Factor:
(c-6)(2c+13) = 0
----
Positive solution:
# of chairs in a row = 6
-----
Solve for "r":
r = 2c+1
# of rows = 2*6+1 = 13
--------------------
Cheers,
Stan H.
------------