An introduction to exponential equation

a) $9^x=2 \Rightarrow x=log_9 2$

b) $3+(5-2)^y-1=\dfrac{25}{5}$

Because of the hierarchy of the operations we firstly do what is in brackets: $(5-2)=3$

and then the quotients: $\dfrac{25}{5}=5$

Re-writing and operating: $3+3^y-1=5 \Rightarrow 3^y=3 \Rightarrow y=log_3 3=1$