Answer:
number of chairs per Row = R
number of Rows = r
R = 2r-3
"three less than twice" = 2r-3
we have two variables. so to solve this, we need another equation.
We know the total number of chairs is 54.
R*r = 54
"Number of chairs per row * the number of rows will equal the total number of chairs.
Now, substitute the top equation into the lower equation and solve.
R*r = 54
(2r-3)*r = 54
2r^2 - 3r = 54
2r^2 - 3r - 54 = 0
solve the quadratic equation:
r = 6 or -4.5
since r = number of rows, then r cannot be negative.
has to 6.
so rows ar 6.
# of chairs per row is
R=2r-3 = 2*6-3 = 12-3 = 9
6 rows, with 9 chairs per row,
that's 6x9=54 total chairs, so it checks out!
