How Do U Solve 3x-4=5x+8?

(4x+2)(3x+5)

I'm just going to show you the math to it I can't explain with words
3x-4=5x+8
  +4    +4
3x=5x+12
    -5x
3x=12
x=4

You write all the numbers with x on one side, and all the numbers without x on the other side, but when you are switching places of numbers above equality sign you have to change algebraic sign
for example     
  3x-4=5x+8
you put 3x and 5x on one side, and 4 and 8 on the other side
and you get   3x-5x=8+4
3x didnt move above the equality sign so you don't change his algebraic sign but 5x did so you get
-5x     ... Also 8 didnt change his place, but (-4) did so you change it to 4.
Then you add or deduct numbers and you get
  -2x = 12   you divide it with 2
  -x = 12     
so   x = -12

3x-4=5x+8
3x-5x=8+4
-2x=12
x=12/-2
x=-6