Laplace transform help...

Hi,

I'm doing some calculations for a circuit but need to use laplace which i have always been very rusty on and haven't used for many years.

The transform of the response of a linear system when the input is a unit impulse is 50/(1+2s)

How do i calculate the steady-state output? and the value of the time constant?

How do i convert this equation back into the time domain?

Any help would be much appreciated.

Thanks

25[e^(-.5t)]u(t)

in time domain