Note that the floor part of x will always be an integer, so x must end in .8.
Now, let \(x = a + 0.8\), where \(a = \lfloor x \rfloor\)
We now have the equation \(2a + 0.8 = 4.8\), meaning \(a = 2\), so \(x = 2 + 0.8 = \color{brown}\boxed{2.8}\)