3^(x+1) = 27 (assuming you mean that the 1 is part of the exponent)

(x+1)Log[3] = Log[27] (take the log of both sides)

x+1 = Log[27]/Log[3] (divide by Log[3])

x+1 = 3 (compute Log[27]/Log[3])

x = 2

(x+1)Log[3] = Log[27] (take the log of both sides)

x+1 = Log[27]/Log[3] (divide by Log[3])

x+1 = 3 (compute Log[27]/Log[3])

x = 2