logarithmic equations

有沒有人可以話比我知第三個step怎樣去第4個step
因為我攞住份答案看不明

Q: solve the following logarithmic equations.
log base9 (3x) = lolog base3 6

A: log base9 (3x) = log base3 6
log base3 (3x) / log base3 9 = log base3 6
log base3 (3x) / 2 log base3 3 = log base3 6
log base3 (3x) = 2 log base3 6
log base3 (3x) = log base3 36
3x = 36
x = 12


THX