Log (base3) 81 = x One of the log identities is Log(base x) x = 1 We can rewrite 81 in terms of 3 so that we can use the identity. Log (base 3) 3^4 = x The power rule lets us bring the 4 in front as a coefficient so, 4* log (base3) 3 = 81 4 * 1 = x 4 = x