In a common log we have an unwritten base of 10. That is, filling in our equation correctly, we have [tex]7.5= log_{10} x[/tex]. Logs and exponential functions are opposites of one another, so we can rewrite that log as an exponential function, like this: [tex]10 ^{7.5} =x[/tex]. Doing that math on our calculators we get that x is 31622776.60