First what your gonna do is distribute the Negative into the (6x + 1) So it would come out as -6x-1, so your new problem is going to be 4x-6x-1= 18. after that you can solve for x.
Add 1 to both sides so that you can have x alone. (new problem is now 4x-6x = 19 )
Since 4x and -6x are like terms you can combine them making it -2x (new problem -2x =19)
to get x alone you would divide both sides by -2
making the new problem x= -2/19