Simplify both sides if needed. The left-hand side needs simplification.
4(x - 6)

-2x + 6
4x - 24

-2x + 6
All is left to do is add and subtract to get the x variable all alone.
4x - 24

-2x + 6
6x - 24

6 <-- Add 2x to both sides
6x

30 <-- Add 24 to both sides
x

5 <-- Divide both sides by 6
In order to be in the solution set, x has to be less than or equal to 5.
In interval notation: [5, -∞)
The answer is 2.5. Just make 5 and 2 0.4 as a ratio