take the log of both sides

but now, one of the log rules says that

so and so just divide by 4 and x=

in general though, people seem to like to reduce logs for no reason that I can see... so log4= so x=

divide by 4 and log(x-4)=4, now raise each side to a power of 10, so

so x-4=10000, and x=10004