+6250 \(23(0.94)^x = 15\\ (0.94)^x = \dfrac{15}{23}\\ x\log(0.94) = \log\left(\dfrac{15}{23}\right) = \log(15)-\log(23)\\ x = \dfrac{\log(15)-\log(23)}{\log(0.94)}\)
You have to divide both sides by 23 and then calc a logaritm (log) with base 0.94 of the right side so its gonna be x=log0.94(15/23) web2.0calc doesn't have an option for any base of logarythm so you can just calc ln(15/23)/ln(0.94) and the answer won't change. By the way answer is around 6.908.
