Express 125 = 5x as a logarithmic equation

I guess the original expression is 125 = 5^x

If you apply logarithms to both sides, you get:

log (125) = x * log (5) < logaritmic equation

=> x = log (125) / log(5)

Given that 125 is 5^3

you can simplify to

x =  log (5^3) / log(5) = 3 log (5) / log (5) = 3 * 1 = 3

There you have the expression as a logarithmic equation and the solution of the equation.