arithmetic
posted by soka on .
PLEASE I REALLY NEED HELP WITH THIS
The seats at a local baseball stadium are arranged so that each row has five more seats than the row in front of it. If there are four seats in the first row, how many total seats are in the first 24 rows?

it is an arithmetic series, with distance 5, and you want the sum of n=24 rows.
Sum=n/2 (a1+an)
where an=a1+d(n1)
an=4+5(23)=119 check that
sum=24/2 (123)=12*123
check all that. http://www.purplemath.com/modules/series4.htm