Wht is 3.175 subtracted 81?

Given the function f(x) = log base 4(x+8) , find the value of f^-1(2)

Scott’s bank account showed a balance of $750 on sunday. during the next five days, he made one deposit of $140 and numerous withdrawals of $180 each. let x represent the number of withdrawals that scott made. write an inequality that can be used to find the maximum number of withdrawals that scott could have made and maintain a balance of at least $100. do not use a dollar sign ($) in your response.

Me because i don't understand how to do it.: )