In a certain conference room each row of chairs has the same number of chairs, and the number of rows is 1 less than the number of chairs in a row. How many chairs are in a row?
1)There is a total of 72 chairs
2)After 1 chair is removed from the last row, there is a total of 17 chairs in the last 2 rows.








let there be x chairs in each row, therefore there are x-1 rows. Total chairs in room x(x-1)

1) x(x-1)=72, x=9;suff

2) x+(x-1)=17,x=9;suff

Hence D