but this is the last problem, so I'll be done after thins one. :) You're at a concert at a distance of 10m away from the band and their sound level is 120dB. How far back do you have to move if you want the sound level to be 85 dB?

Question

but this is the last problem, so I'll be done after thins one. :) You're at a concert at a distance of 10m away from the band and their sound level is 120dB. How far back do you have to move if you want the sound level to be 85 dB?
I tried using 85=(10/r1)^2, but this doesn't seem to be working.