Logs are the inverse functions to exponents
𝑓𝑥=log𝑏𝑥 and 𝑔𝑥=𝑏𝑥 are inverse functions
(where 𝑏>0 and 𝑏≠1)
𝑓∘𝑔𝑥= 
𝑔∘𝑓𝑥=