25=286.93(9.738^x) divide both sides by 286.93
25/286.93 = 9.738^x take the log of each side
log [ 25/286.93] = log [9.738]^x and we can write
log [ 25/286.93] = x * log [9.738] divide both sides by log [9.738]
log [ 25/286.93] / log [9.738] = x = about -1.072
