So, it's late and I'm only gonna answer #9. If there are 50 rows and the first row has 20 and the rows get larger, then each row has at least 20 seats. 50 X 20= 1,000. Now, row two has 1 additional seat than the first row, row three has 2 additional seats than the first row. So, take 1000+1+2+3....and so on until you get to +49. There's your answer.
