Rearranging a Logarithm Functon

[SHRock]

Homework Statement

y=ae^x

Homework Equations

rearrange to find a

The Attempt at a Solution

y/a=e^x

x=ln(y/a)

x=lny-lna

lny-x=lna

now how do I rearrange/inverse to seclude a

 

[yungman]

$$ln(y)-x = ln(a) \Rightarrow\; a = e^{ln(y)}e^{-x} = ye^{-x}$$