Question 1111088
 there are 40 seat in the first row,
42 in the second row and so on. 
If there are 25 rows 
standard ticket price is $150 per seat, 

Total number of people when sold out

The seats are in arithmetic sequence

a= 40
d=2
n=25
The total {{{Sn = (n/2)(2a+(n-1)d)}}}

= {{{(25/2)(2*40+ (25-1)2)}}}

= 25 * 128/2

= 84*25 seats -> 2100

multiply by 150 to get the revenue