When adding adding logs you can combine them like this
Log(x)+ log (x-3)= log ((x(x-3)
Now we can set that equal to log (7x)
Since both logs have the same base we can get rid of the log
X(x-3)= 7x
X^2-3x=7x
X^2-10x=0 factor out an x
X(x-10)=0
Therefore x= 0,10
Since log 0 is undefined that means it does not work
So the only answer that works is 10
