simulink dynamical modeling blocks

I'm using simulink to model the following:

U(s) ------> 2s+6 ------> X(s)

So the input U(s) multiplied by (2s+6) gives the output X(s). Now my problem is which block in simulink allows me to write (2s+6)? Should it be a gain? But then gain blocks require a numerical value, and this 2s+6 obviously has s. How do I do this. THanks.

I'm trying to use the transfer function but its in fraction form and it keeps saying the denominator has to be a greater power than the numerator.

[Azzi Abdelmalek]

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