Increasing Row Size.... 1. The problem statement, all variables and given/known data There are 150 rows at a concert hall. Each row you move back there is an increase of 10% in the number of seats. The first row has 100 seats. How many seats are there in the concert hall? 2. Relevant equations I don't know the equation to represent this change. 3. The attempt at a solution Obviously I could go through and do each rows amount of seats, but I'd like to know the equation that will solve this. Is it n(n+1)/2?