What's the fastest way to solve this problem?

[hengirl03]

If the attendance at a school had increased by 30 percent over last year, this year's attendance would have been 10,792. Actually the attendance decreased by 35 percent from last year. What is this year's attendance?

A: 5,126
B: 5,206
C: 5,486
D: 6,136
E: 6,300


What would be the fastest way of approaching this problem, and will that method work for all problems of this type. The answer is C.

[rs2010]

You have 1.3 of something and you need .65 of it.

Method is up to if you find calculation easy then it wont take more than 60 seconds.