Architecture: In a 20-row theater, the number of seas in a row increase by three with each successive row. The first row has 18 seats:
a. Write an arithmetic series to represent the number of seats in the theater.
b. Find the total seating capacity of the theater
c. Front row tickets for a concert cost $60. After every 5 rows, the ticket price goes down by $5. What is the total amount of One generated by a full house?!

I have A it is 18+21+24....+75
But I need help b and c

Question

Architecture: In a 20-row theater, the number of seas in a row increase by three with each successive row. The first row has 18 seats:
 a. Write an arithmetic series to represent the number of seats in the theater.
 b. Find the total seating capacity of the theater
 c. Front row tickets for a concert cost $60. After every 5 rows, the ticket price goes down by $5. What is the total amount of One generated by a full house?!

I have A it is 18+21+24....+75
But I need help b and c

mertsj · Answer

Use the formula for the sum of a arithmetic sequence