Question 167030
Let x=number of rows
Let y=number of chairs per row
xy=54----------------------------------eq1
and
y+3=2x---------------------------------eq2
From eq1, we see that y=54/x.  Substitute this into eq2:

54/x + 3=2x  multiply each term by x
54+3x=2x^2  subtract 2x^2 from each side

-2x^2+3x+54=0  multiply each term by -1
2x^2-3x-54=0---------------------quadratic in standard form and it can be factored
(2x+9)(x-6)=0
x=6--------------------------number of rows
Forget the negative value for x.  Rows are positive and besides we can't have fractions of rows
Substitute x=6 into eq1:
6y=54
y=9----------------------------number of chairs per row
CK
The number of chairs per row is three less than twice the number of rows.

9+3=2*6
12=12
also
6*9=54
54=54


Hope this helps---ptaylor