If you are looking to find the value of x then you have to use distributive property.
1st: multiply -3 by 2x and 4 -3(2x+4)
-6x -12
2nd: do the same thing on the other side which is multiply 3 by x and -6
3(x-6)
3x-18
3rd: Then you have -6x-12=3x-18
+12 +12
add 12 to each side so then you have -6x=3x-6
then divide by -6 on each side and the answer is x= 2/3