PLS help asap, brainliest goes to whoever properly explains their answer! (i know the answer is x=3 but i don't know how to get there)

Wendell is looking over some data regarding the strength, measured in Pascals (Pa), of some building materials and how the strength relates to the length. The data are represented by the exponential function f(x) = 2x, where x is the length. Explain how he can convert this equation to a logarithmic function when strength is 8 Pascals.