Paula opens a bank account that earns 6% interest. Her initial deposit is $400. How much money does Paula have after 15 years?

Tim's phone service charges $23.06 plus an additional $0.22 for each text message sent per month. if tim's phone bill was $28.56, which equation could be used to find how many text messages, x, tim sent last month?

Can someone explain to me how to do

Write the equations in logarithmic form 9^4=6,561