i can't figure this equation out

 25=10(log(i)+16)

$25=10\left(\log(i)+16\right) \\ \dfrac 5 2 = \log(i)+16 \\ -\dfrac {27}{2}=\log(i) \\ \mbox{Assuming we are using logs base 10 we have } \\ i = 10^{-\frac {27}{2}}$