It is easiest to take this one side at a time
Factor the first and second expressions to get
3x(x+1)/(x+1)(x+7)
Cancel the (x+1)
3x/(x+7)
Now the other side
factor both terms again to get
3(x-5)(x+5)/(x-5)(x+7)
Cancel the (x-5)
3(x+5)/(x+7)
This is what we have left
3x/(x+7)
------------
3(x+5)/(x+7)
Now we can cancel the (x+7) as well as the 3
This leaves us with x/(x+5)