Question

A theater has 30 seats in the first row, 33 seats in the second row, 36 seats in the third row, and so on in the same increasing pattern. If the theater has 15 rows of seats, how many seats are in the theater?

Answer 1

Just keep on adding

30 + 33 + 36 + 39 + 42 + 45 + 49 + 51 + 54 + 57 + 60 + 63 + 66 + 69 + 72

= 765 seats.