First, we need to determine if the sequence is an arithmetic or a geometric. So the arithmetic sequence is referred to a sequence that the difference between the numbers is constant. While the geometric sequence is a sequence where each number after the first is identified by multiplying the previous one by a fixed number. 
 Given 
  57, 61, 65   the difference between the numbers is 4
Solution
Arithmetic sequence
An= 65+4     An= 69+4    An= 73+4    An= 77+4     An= 81+4     An= 85+4
An= 69         An= 73         An= 77        An= 81          An=  85       An= 89  
The score of Edgar for his 9th quiz is 89 points.